I don't know if there are two types of Gem blades being sold, or what, but the Gem by Persona sold at my local Walgreen's are very different then the blades that came from Ted Pella. They aren't as good of performers, and even a quick look will show you the they have different angles on the edge.
Do the Walgreen's say "SUPER STAINLESS". My understanding is that the SUPERs are PTFE coated. There are GEM stainless that are not PTFE coated. You can even get them from Pella (http://www.tedpella.com/dissect_html/dissect.htm#_121_2).
If the ones you have seen say "SUPER STAINLESS" and are in any way different from the Pella PTFE stainless blades it would be quite interesting to know that. Pictures please!