Facebook is testing a way to show users how they are connected to people who comment on their friends’ posts. In a few instances, we’ve seen comments displaying descriptions like “2 mutual friends” next to a person’s name.

This is an obvious way for the social network to encourage people to add more friends and could mean the company is looking to make comments on the site more like comments on third-party websites.

The test could also be a response to the “subscribe” feature. Now that users are able to share posts with subscribers and allow anyone from the public to comment on them, showing commenters how they are related to one another could help put the discussion in perspective.

Facebook’s comments plugin for third-party websites and applications began showing additional information — job title or school for instance — about commenters in March 2011. The plugin also orders comments by social relevance, pushing comments from your friends to the top. Facebook did something similar with the “Top Posts” filter on pages last year, but has not applied it to comments on the site, which continue to be displayed in chronological order.

This latest test could suggest Facebook is looking for a way to make these products more similar. Adding social context to comments on posts from pages and users who accept subscribers would maintain the feeling that Facebook is a place to connect with people you know. Otherwise, with more content being made open to the public, some users might be hesitant to join comment threads that include people they don’t know.