File name Prefixes in elements 2020

I understand that the backup of a catalog assigns a "B" prefix to a filename.  Why does elements 2020 assign a "P" to some  files?  Is this just another backup connotation?  I am trying to clean up my organizer and noticed many files with this Pxxxxxx and wonder if it is safe to remove from the catalog because there is a duplicate of the photo with a "normal" file name sequence.