USA and Australia are both stillborn, and their respective New England regions become independent republics.
USA doesn't end up going with the name "USA", and instead favors Columbia. Queue eternal confusion with the Spanish Colombia a few decades later.
At one point, the Philippines had planned to rename itself to Malaysia, before the current country with that name became independent. Perhaps in another world, the Filipinos went through with it anyway.
An earlier and more successful Greek Revolution, which leans harder into their Byzantine heritage and names their country Rhomania, while the Romanian principalities still end up unifying later on.
There's also OTL with Republic of Congo and Democratic Republic of the Congo, with each state forming from separate colonial holdings.
These technically goes against them being historically and etymologically different, though. But if so, I guess the two Galicias are technically disqualified too.