[ISHMap-List] Distinguishing between loose leaf maps from 1513 and 1520 Ptolemy

[Ron Hekier]

I have a map reported to be from the 1513 Ptolemy by Waldseemuller.
Is there any way to distinguish loose leaf maps from either the 1513 and 1520 editions of Ptolemy?
There was no text on the verso of the maps of these editions and the 1520 is widely reported to have been printed from the 1513 blocks.
Any replies are appreciated.
Regards, Ron Hekier