Two or more yanderes aim for the same guy/girl. Anything's fine as long as it ain't yaoi. Yuri, shoujo ai, and shounen ai's fair game.
Kuro no Maou? Edit Sadly Asian hobiest took over it.. It's hard to read in their site, and if you read it in any dark site it's still hard.
https://www.novelupdates.com/series/broken-winged-angel/ I don’t know if it is exactly what you want but this novel has 2 crazy Yandere ( twins or brother?, don’t remember which one) but for one girl. Or are you looking for two distinct love interests chasing?
Experimental Log of the Crazy Lich Isn't the main premise though, and the second yandere only gets introduced ~200 chapters in.
Running Away From the Hero has quite a few yanderes pining after the MC. There's even a side character with his own group of yanderes. I'm convinced every woman in that novel has yandere potential