After getting about 100 cards, I did run into the problem described by HCWT. Weirdly enough, it appears that the game just sees certain CDs as identical to one another. Some preliminary findings:

1)I only have 3 monster cards, the ones given me a the BC Center. I have gotten tech cards for all monster types.

2)I never had the problem with PSX games, and I got many duplicate cards from different CDs. (Check the CD list, I'm still working off of one game save!)

3)I had run 6 DC GDs through the shrine before I hit my first 'already taken' warning. (Armada, Chef's Luv Shack, Incoming, Crazi Taxi, HoD2, and Blue Stinger. Wetrix, was the one I was told had already been used.)

4)I did get duplicate cards from DC GDs. (Rayman 2 and Official DC magazine #4 both gave me Tiger's Horn, no problem.)

4)My very first PC title gave me the warning. It was Official DC Magazine #1, which is a PC CD.

My only conclusion right now, is that whatever the game is looking at on CDs can give the system a false message that 2 CDs particular CDs are identical.

I was wondering about this last night. If the game "knows" that you've shrined a cd before, it must be able to store the cd's signature in your saved game file. The saved game file is only one block so the signature must be very small indeed. Lets suppose that there are ? signatures possible for each card plus signatures for cards won in battle. If the signature is small, then there will be a fair number of duplicates for cd's that are similair in nature.

It might be a good idea to start up a second game just to test out cd's that give the duplicate message.

I'll start a second game as soon as I'm done with the sections on this board. Interestingly enough, I still have not gotten a duplication message on a PSX CD.