Board Thread:Questions and Answers/@comment-25001290-20160627214958/@comment-26091443-20170304031116

It's been pretty clear that you can't. The closet thing seems to be cases like Todoroki, and even functionally he seems to have two, genetically he's just the result of two Quirks merging into one, which is very obvious with the way his power functions.

I know this is old but I still feel the need to point out that what GreatestSin said is wrong. They series has never treated things like Tokoyami having a bird head as Quirk onto itself. Some people's Quirks seem to also alter their bodies, but his bird head and Dark Shadow aren't treated as separate things.