I don’t understand why he’s on the ballot for a different party.
He's a sore loser swamp creature who think he owns that seat.
I live in NYC and candidates are often listed on multiple parties on the ballot. You’ll often see the Republican also listed as the Constitution party candidate and the Democrat listed as the Green party and Working Families party candidate for example.
Here’s what it says in Wikipedia:
Like other minor parties in New York, the Independence Party sometimes nominates its own candidates and sometimes endorses one of the major party candidates using electoral fusion. The listing of a major-party candidate on the Independence line can be seen as an indication of that candidate’s friendliness to centrist views.
Electoral fusion is an arrangement where two or more political parties on a ballot list the same candidate, pooling the votes for that candidate.