This is the generic photo specification for IRCC. It doesn’t say 2 photos. Instead it says to provide the correct number of photos specified. Secondly, studio stamp and applicants name, dob and uci should be on the back of the one photo. It doesn’t say studio stamp should be on one photo and applicant detail on second photo.
Moreover, IRCC usually requests two photo while they are issuing PPR request. In the two photos, one will be stamped on CoPR and the other will be used for PR card. In our case, we already got CoPR and only need photo for PR. So it doesn’t make sense to request two photos.
This is just my view and already sent my one phot and CoPR to IRCC. So if you feel it require two phots, please send two.
Thanks