I have the default “AnimationAssets” folder with a standard UE4-skeleton and some animation and I added another folder to the project called “AnimStarterPack” which also contains a default UE4-skeleton with more animations.
I believe that the 2 folders actually have the exact same skeleton only they are different imports.
I noticed that in my AnimationAssets-animation persona I could not see the animations from the other folder:
This is probably because I have to retarget them from the UE4-skeleton to the other UE4-skeleton. So I rightclicked a random animation from the “AnimStarterPack” and select “Retarget anim assets”. Then I get a window where I can retarget it to the other UE4-skeleton but the list of skeletons is empty?
Here are the folder views of the 2 skeletons (which should probably be duplicates of each other I assume):