I'm with VaeVictis. My HotAC group(s) allow multiple uniques, as differnt combos sometimes require the same card to work. My PS9 Y-wing has Jake, Biggs and Poe (and R5-P9), while a B-wing has Jake and Calculation and Ten. Both don't need Jake, but both are made better by it's use. One tanks while the other kills. If we made uniques unique, one player or the other would be left out just because they did not get there first.
If everyone in the group was tryingt to make the excat same build, I could see reason to change it. Cookie cutter lists get boring no matter what you are going, co-op or skirmish.
Edited by Salted Diamond