(Speaking in general terms rather than twoto the specifics.)
If someone copies part of an answer but correctly references it (credits the original author) and quotes the part they took (typically using a blockquote), that's usually fine unless that's essentially the entire answer.
There's several things to do if someone copies a whole answer:
- dealing with the copied answer
attempt to guide the poster (e.g. comment to let them know that this is not a suitable thing to do, and explain how to quote and reference what they need, or to flag as duplicate if the question is a duplicate), and
either edit to quote and credit (where suitable), or
vote to delete or flag to delete or flag to convert to a comment (e.g. if the copied answer is only somewhat relevant rather than a real answer)
- a copied answer typically indicates a duplicated question; if that's the case
flag as duplicate, vote to close as duplicate, or mark as duplicate if you have a relevant gold tag badge if this is the case
if the question is essentially an exact duplicate and has very good answers that would therefore answer the original that it's a duplicate of, you may want to ask for a merge; flagging to close as a duplicate (etc) as above is still the first thing to do.