Yes, when someone else has already posted an applicable comment (either a canned one, or manually written), selecting the "no comment needed" option is totally appropriate. In fact, [the review system detects and prevents duplicate canned comments][1].

On the other hand, if the existing comment is manually written, adding a canned comment can sometimes be helpful if it explains the problem in more detail or offers useful links (e.g. to the FAQ or some Meta post). When in doubt, I'd say err on the side of more information for the author of the post, rather than less.

If you want, you can also go and upvote the existing comment, to add more weight to it.


  [1]: https://meta.stackexchange.com/q/143669