Fritsch cards has a little blurb about these in their description:
https://fritschcards.com/1992-barry-colla-postcard-single-tony-gwynn/
From listings on Fritsch, ebay, and COMC, these players exist:
Griffey #11792 (portrait with bat on left shoulder)
Griffey #6492 SN4000 (batting)
Gwynn #6592
Ripken #6692
Ryan #6792
Thomas #7092
Based on the gap in numbering between Ryan and Thomas, there are probably at least 2 more. Not sure why the first Griffey doesn't follow the sequence of the others, but the card design and copyright year are identical to the others. This isn't the first Colla issue I've seen with screwy numbering.
Collecting Roberto Alomar cards since 1990.
The Roberto Alomar Baseball Card Reading Room:
firnquake.wix.com/alomar