Board Thread:FAQs/@comment-26261770-20180128201431/@comment-27144409-20180202124010

It's possible that if Amber's Aura had ben completely transferred to Pyrrha without interuption, and Pyrrha lived, that she might have had two Semblances since she would have the Auras, the manifestations of the soul, of two people. That said, that outcome is highly theoretical since we didn't see the final results of a successful transfer.

While there might be some circumstances where it could possibly happen, I'd generally give it a wide berth.