Tesla and Edison for sure.
I would say Rosalind Franklin and Watson/Crick would be a fair rivalry. Everyone at the time was speculating what DNA actually looked like structurally, and there was certainly lots of credit and praise going out to the first one to discover it. Watson and Crick literally made goody-goody with Rosalind to get a look at her x-rays and without telling her what they deduced they published their work on the double helix.
Tons of bands/artists. I'd nominate Cobain/Vedder, Tupac/biggie, Spears/Aguilera
Tons of athlete's too. Like, Kobe/any headline ball player who's played Kobe
i'd reserve Michael Jordan with Larry Bird though
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lol j/k - Bacon trolling Crono fans