Do they have the same name but are saved in different folders?
If not, what properties do you want to sort by?
Have you tried the various 'Arrange by...' options found when you right-click in your Pictures Library (not the folder)?
Or, in your Pictures folder, type:
kind:picture
to get a flat view of all the pictures in all the various sub-folders and be sorted on any property:
If not, give us a better idea of what you want to do.
Keith