Can more than one unit do a quest?

Not at the same time. Definitely only 1 unit on each Quest card. You can have multiple copies of a Quest (Max 3) in play, each with 1 unit on it. So far, no cards ever remove a Quest card, so the only stoppers for them are:- Remove unit from them which could get replaced, but any resources accumulated are lost, or cancel the Quest card as it was being played. Cheers!

Thanks! I'm quite sure my brother and I have been doing wrong some things in game. Given that i'm the only collector at the local store.
The non Magic Players all seem to collect one LCG atm which is rather funny. ^__^