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[Davo66]

I have had two coastals, (AdultsM/F) together for almost a year and never have they shown any aggression or dominance towards each other. Actually the opposite, they are extra careful when curling up together and if they do smell food and see movement, (the other snake moving) they don't strike they investigate, have a smell, recognise each others scent and loose interest in the movement.
Thats just my situation, both are 7 foot plus. I believe smaller/younger snakes are little more nervous and willing to strike so maybe you shouldn't keep them together, at least not on the first night.

Davo