Doppelgaga
A person who is accused of copying Lady Gaga, whether it be through fashion-sense, music, or mannerisms. It comes from the word Doppelganger, "A word that has come to refer to any double or look-alike of a person," and the word Gaga.
Person A - Did you see Nicki Minaj at the 2011 VMAs?
Person B - Yeah, she was such a Doppelgaga in that outfit.
Person B - Yeah, she was such a Doppelgaga in that outfit.