I have a TSR cube, but when I loaded the list into a deck, it grouped eight cards by themselves in an untitled group at the top (see here https://deckbox.org/sets/3875229?s=n&o=a) .

Each one is different. The only thing I can think is that two of them have type updates (Tribal -> Kindred and Viashino -> Lizard), but that doesn't explain the Urza's Factory.

Cheers!