When clicking execute on a updater item in the registry the tree shows it twice in the queue

The tree with updater items seems to be rendered twice.

Steps to reproduce:
1. login as admin into the archetype CMS
2. navigate to the Updater Editor
3. click the 'New' button

Expected: a single new script is added to the registry
Actual: all items in the registry are shown twice (see screenshot)

When the CMS is started in Wicket development mode, the following stacktrace is shown after step 3:

Unexpected RuntimeException

Last cause: The component [WebMarkupContainer [Component id = indent]] was rendered already. You can render it only once during a render phase. Class relative path: org.apache.wicket.extensions.markup.html.tree.DefaultAbstractTree$1:root:tabs:panel-container:cards:5:panel:panel:updater-tree:i:8:indent

Stacktrace

Root cause:

The component [WebMarkupContainer [Component id = indent]] was rendered already. You can render it only once during a render phase. Class relative path: org.apache.wicket.extensions.markup.html.tree.DefaultAbstractTree$1:root:tabs:panel-container:cards:5:panel:panel:updater-tree:i:8:indent
MarkupStream: [unknown]
at org.apache.wicket.Page.componentRendered(Page.java:210)
at org.apache.wicket.Component.rendered(Component.java:2609)
at org.apache.wicket.Component.internalRender(Component.java:2382)
at org.apache.wicket.Component.render(Component.java:2306)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1390)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1554)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1529)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1484)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2548)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1493)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree$TreeItem.onRender(AbstractTree.java:231)
at org.apache.wicket.Component.internalRender(Component.java:2378)
at org.apache.wicket.Component.render(Component.java:2306)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree$TreeItemContainer$1.visitItem(AbstractTree.java:433)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree.visitItemAndChildren(AbstractTree.java:1730)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree.visitItemChildren(AbstractTree.java:1748)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree.visitItemAndChildren(AbstractTree.java:1731)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree.visitItemChildren(AbstractTree.java:1748)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree.visitItemAndChildren(AbstractTree.java:1731)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree.access$400(AbstractTree.java:67)
at org.apache.wicket.extensions.markup.html.tree.AbstractTree$TreeItemContainer.onRender(AbstractTree.java:438)
at org.apache.wicket.Component.internalRender(Component.java:2378)
at org.apache.wicket.Component.render(Component.java:2306)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1390)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1554)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1529)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:689)
at org.apache.wicket.markup.html.panel.AssociatedMarkupSourcingStrategy.renderAssociatedMarkup(AssociatedMarkupSourcingStrategy.java:76)
at org.apache.wicket.markup.html.panel.PanelMarkupSourcingStrategy.onComponentTagBody(PanelMarkupSourcingStrategy.java:112)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2548)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1493)
at org.apache.wicket.Component.internalRender(Component.java:2378)
at org.apache.wicket.Component.render(Component.java:2306)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1390)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1554)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1529)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1484)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2548)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1493)
at org.apache.wicket.Component.internalRender(Component.java:2378)
at org.apache.wicket.Component.render(Component.java:2306)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1390)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1554)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1529)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1484)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2548)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1493)
at org.apache.wicket.Component.internalRender(Component.java:2378)
at org.apache.wicket.Component.render(Component.java:2306)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1390)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1554)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1529)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:689)
at org.apache.wicket.markup.html.panel.AssociatedMarkupSourcingStrategy.renderAssociatedMarkup(AssociatedMarkupSourcingStrategy.java:76)
at org.apache.wicket.markup.html.panel.PanelMarkupSourcingStrategy.onComponentTagBody(PanelMarkupSourcingStrategy.java:112)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2548)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1493)
at org.apache.wicket.Component.internalRender(Component.java:2378)
at org.apache.wicket.Component.render(Component.java:2306)
at org.apache.wicket.ajax.XmlAjaxResponse.writeComponent(XmlAjaxResponse.java:127)
at org.apache.wicket.ajax.AbstractAjaxResponse.writeComponents(AbstractAjaxResponse.java:212)
at org.apache.wicket.ajax.AbstractAjaxResponse.writeTo(AbstractAjaxResponse.java:144)
at org.apache.wicket.ajax.AjaxRequestHandler.respond(AjaxRequestHandler.java:363)
at org.hippoecm.frontend.PluginRequestTarget.respond(PluginRequestTarget.java:138)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:861)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:97)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:261)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:218)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:289)
at org.apache.wicket.protocol.http.WicketFilter.processRequestCycle(WicketFilter.java:259)
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:201)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:282)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.hippoecm.frontend.plugins.login.ConcurrentLoginFilter.doFilter(ConcurrentLoginFilter.java:54)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.__invoke(StandardContextValve.java:123)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.__invoke(StandardHostValve.java:171)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)