I believe you can use one as an artifact and one as an enhancement at the same time with both working properly. You could do it in a T1 deck that had 100+ cards as well.
Unfortunately, this is incorrect.
All Artifact, Covenant, Curse, and Fortress cards are considered unique. A player may control only one of these at any time. However, unique Artifact, Covenant, and Curse cards can be duplicated face down in the Artifact pile.
A Covenant or Curse is
always a Covenant or Curse, regardless of how it is being used. Therefore, since all Covenants and Curses are unique, you cannot have one active as an artifact
and play one as an enhancement. Technically, you can't even play two of the same as an enhancement at the same time, per the current rules.
Maybe that should be looked at, but that is the current rule.
