Steps to reproduce:

1. Create a content item with richtext field
2. In richtext field create 2 lines with text (also, separate them by some empty lines)
3. Select both lines with text and add image to them by 'Upload image' button
4. Drag  image from one line to the other

Actual result: 

Dragged image overlaps an already existing image

Expected result:

Both images are visible.

 UPDATE
Error also occurs, if user has multiple images in RT and drags oone of them -> then dragged image stays visible, the others are not visible then.