Currently Guru badge description looks as:
Accepted answer and score of 40 or more. This badge can be awarded multiple times.
According to the answer that excludes self-accepted answers. Hence I suggest to clarify such a nuance in the badge description. E.g. change the first sentence to the following:
Accepted answer by another user and score of 40 or more.
This current feature request is not a duplicate of another because the root part of this one - to point out that the answer must be accepted by someone else. This part doesn't mentioned at all in another FR.