I don't see a problem here. There are some cases when I sometimes answer questions and at the same time VTC as a duplicate.
###A question can be answered shortly, but the duplicate question has a good but a very complex answer.
A question can be answered shortly, but the duplicate question has a good but a very complex answer.
A perfect example is Installing Broadcom Wireless Drivers
OP shows that they need bcmwl-kernel-source
and it this easy answer is better for the OP than a long manual about these drivers. Not everyone can understand it all, including Secure Boot issue, etc.
Same is about Nvidia drivers with top answer being not quite good, because of being a bit obsolete.
###I know the question is a duplicate, but can't find of which one.
I know the question is a duplicate, but can't find of which one.
In this case I prefer to give an answer. If someone marks the question as a duplicate, nothing is wrong. I can find it later and do it myself.
So I do not think it is a problem at all.