I believe the rule is cards that say may be used twice per game count their uses for all copies of that card, whereas cards that just say may be used twice are limited per copy.
Agree. If the card says "may be used X per game", that applies to
all copies. Captured Ark is an example of that type.
Other cards say that they "may be used X times" or "may be used X times and then must be discarded". For these cards, if they have their count reset (discard, return to hand/deck), or another copy is used, then you can again use them X times. Example: Promised Land has a 2 use, then discard clause. If it is brought back after being discarded, you can use it twice again.
Type: Site • Brigade: Multicolor • Ability: None • Class: None • Special Ability: Hero gains access to any site. Abraham, Isaac, Jacob, Joshua, and King David may use Promised Land without limit. May only be used twice by other Heroes, then it must be discarded