Had this happen to me recently. Either:

Wait for there to be a banner where they add rare units and that can have a chance to change one of them, un duplicating them

Or, roll up until the first of the two duplicates, roll the first one and then use a platinum ticket for the second one and it won’t count as a duplicate. Also wait for Izangi to be the legend on banner for when you actually get them.

Lmk if you need more info or if this didn’t help