As card collector's we're all very familiar with parallels. The slightest variation creates a separate card and it gets added to a checklist.
Here's an example.
It doesn't scan well but the card below is a 1st Edition parallel to the base 2004 Topps card above. The only difference between the two cards is that little bit of foil.
So here's a question for you. Do you consider the cards below the same card or a different card? They are 2010 Topps Attax cards and each feature a unique code to be entered online. Does the code make each of these cards a unique card?
To me the difference between the two is bigger than the difference between the 2004 Topps and the 2004 Topps 1st Edition. I don't think they are two different cards, but it did make me think for a minute and I thought I'd pose the question to the card blogosphere.