So today:
Oculus: x3
Azjol-Nerub: x3
CoT : Stratholme: x3
Old Kingdom: x2
Drag'Tharon Keep: x2
Gundrak: x2
Violet Hold: x1
And for the record, I have unlocked the new dungeons.
This leaves following unlocked:
Frozen Halls (3) , Utgarde (2), Nexus, ToC, Ulduar (2) = 8 unused dungeons.
Wasn't the system meant to prevent this?