The problem is you can stack cards when you sell. Most people won't go buy 4 cards of Hackenberg, but it's really easy to stack 3-4 of the card, then sell all of them at same exact time. Last year you would know if you saw 4 or 5 in a row at the exact same time, you knew it was the servers generating the card. Maybe ask people in your league to post random cards at astronomical numbers and see if you find their card. They could be wrong about their server. If you check with a second and third person, and get same result, then you'll know it's right.