When you have multiple images, some disappear after editing a saved document

1) Open the Xinha editor of an empty content field
2) Add an image with insert/modify Image
3) Click done
4) Edit the content again by clicking on the editor
5) Add an image with insert/modify Image
6) Click done

The new image replaces the old (first) image. This due to the fact that the old image is still selected in Xinha editor

WORK AROUND:
First add some text to the field
Make sure the image is no longer selected by adding text or space after the first image and then inserting a second image.