I'm guessing it's dating someone who looks either exactly or a lot like you.

i have never heard that expression before but i do like when you see folks who have been together for a long time and they start resembling each other

I suppose it's not much else, except perhaps the use I saw was a bit metaphorical for having the same tastes too. I wondered if it was something common that I had no idea of!

I always hear this when referring to someone with lots of similar tastes, interests and/or habits, like the opposite of when people say ‘opposites attract’

also not purely gay context as I get these dating advice (sayings???) in like both gay and het situations

the term "double", in tumblr otherkin communities, refers to someone who kins as the same thing as you. so like if you kin as say fuckin uhhhh Benedict Arnold you put in your byf (before you follow, which is linked to on the 50px wide sidebar on your pastel tumblr theme) that people who also kin as Benedict Arnold must not follow or even interact with you. presumably this is to prevent the immense psychic trauma one must feel when you become that spiderman pointing at spiderman meme

You know what, now I feel like this was being referenced. Also, someone please smuggle them texts on open individualism or tell them that everything's all just brahman in the end so sharing is not bad.

now I feel like this was being referenced

oh nooo that is like the worst possible outcome of the situation you detailed

Perhaps I should take it back a bit, alluded to. Phew, better.