I'm an idiot and have been using Miracle Amulets on only one duplicate at a time. It never occurred to me to combine the two other duplicates using one amulet in one fell swoop.

On the other hand, unless they are event cards that you can obtain all three copies of reliably, maxing out cards could take a long time, especially considering how uncommon UR draws are.

A bigger gap between whales and the rest of us plebeians, i guess.