[Powerpoint] Detect identical pictures

[Daniel Kirsch]

Is there a way to detect identical pictures used in a powerpoint slide?
Do they reference the same resource internally? And if so, how can I
check that reference?

I'm going through all shapes of a slide and use the "export" command for
all pictures to extract them. This usually leads to a lot of duplicates
which I want to avoid as good as possible.

The only (less elegant and more expensive) solution I found is to export
everything, iterate over all images and compare their checksum and
delete duplicates afterward.

Any ideas?

Thanks
Daniel