Mod Chip vs. Plug Mod ??

[rancidmonkey]

Quick question, any help would be much appreciated...
I recently bought 5 backups from a guy online, and only one of them worked. They aren't Verbatims, and they won't even load up. All my other backups are on Verbatim DataLife CD-Rs, and they work just fine. I'm using a Plug Mod (Action Replay), not an internal mod chip, and when I told the guy this, he said that his website states that I need a mod chip to play the backups sold on his site.

Is there really that big of a difference between the two mods?

Or did I just get some shoddy backups, and the guy is weaseling out of responsibility?

If anyone out there has a mod-chipped 5501 PSX, and would like 4 free games (MTV Music Generator, Metal Slug, Ace Combat 3, and The Next Tetris), I'd love to send them to you, to see if they really do work on a mod-chipped system. Just reply here with your email address.

Thanks for your time, everyone.
-rm