Often there is a situation, when there is already an answer which is correct, but either it's only partial or does not go at all into details, culprits etc.
Which would be preferred way of dealing with that:
- extend existing answer? even if that means your contribution will be actually more then original answer?
- write separate answer without duplicating content of the one(s) already posted?
- write complete answer duplicating content already posted? (won't that be perceived as "answer stealing"?)