And they're 65% alike

Makes sense. They both appear to be chihuahua mixes,..

They are both chihuahua mixes

Queso is 68.1% chihuahua and Salsa is 53.4 % chihuahua

And a lot of the dogs they're mixed with are the same

Queso is mixed with rat terrier and has small poodle, Pekingese and pomeranian in his supermutt mix, Salsa is mixed with Poodle and Pekingese and has rat terrier and pomeranian in her supermutt mix

(They have other breeds as well, those are just the shared breeds)