When people become friends, the activity feed shows redundant stories. This screenshot was taken from this community.
This is a long-standing issue. Re-logging for review.
Essentially, two stories are always created for this type of action as one or both of the parties may not have access to see the other story, and if there are multiple friendings within a window, each story could represent more than just the two parties.
That said, it would be good to review if we can limit showing both when they are redundant.