Yeah, noticed that as well, very possible 
(though obviously there's nothing wrong with that). The user stats, especially the posting activity, are very helpful for discovering alts, and usually when both users go absent at the same time or for the same time periods and come back at the same time it's a very good indication of your suspicions.
IMO both users are very reputable (for different reasons) and the person behind both accounts probably has each of the accounts for different reasons. (though obviously there's nothing wrong with that). The user stats, especially the posting activity, are very helpful for discovering alts, and usually when both users go absent at the same time or for the same time periods and come back at the same time it's a very good indication of your suspicions.