I reviewed the first post of a user (this answer). They asked a question on SO and posted an answer a day later (and marked it as the accepted answer).
Then today he answered a question here on GDSE with essentially the exact contents of his Stack Overflow answer (along with a link to it).
Would have it been better to only give a small explanation, with a link to the existing SO answer, or is copy/pasting the text of the answer on SO appropriate?
I thought the second option would be the most appropriate (because you don't want to oblige your readers to go somewhere else), but at the same time, duplicating content on Stack Exchange seems unnecessary.