On my first go-through, I didn't know I needed to keep track. I didn't want to do a whole new game, so I watched some YouTube videos that walked-through collecting the treasures. It appears to be the second datadisc counting twice.
The first datadisc is in the alcove with the Rancor (4 DATADISC - 1/7 treasures).
The second is in the cavern with all the clay pots. If you take the left fork of the tunnel into this cavern and break the clay pot with a lid, you get a second datadisc (5 DATADISC - 3/7 treasures). So, this seems to be the one that counts twice.
The next clay pot with a lid (6 DATADISC - 4/7), the next pot with a lid by the purple, electrified door (7 DATADISC - 5/7), and the last clay pot with a lid right outside the elevator (8 DATADISC - 6/7 treasures), all seem to count as one each. The final one, after falling through the floor where you need to get through the purple, electrified doors (9 DATADISC - 7/7 treasures), also just counts as one.
@b2dc592c85999308 Thanks for the info; that's definitely helpful. Hopefully it gets to the QV team or whoever needs to look into it.
