It would be great if there was more automation in linking existing users to their other profiles on StackExchange.
For example, this user on Area 51 is this user on StackOverflow, but his reputation isn't showing. Likewise
and maybe some others just in the Mathematica proposal alone.
Meanwhile this user has inadvertently managed to commit twice, because he previously committed as an unregistered user.
A simple fix would surely be that users had to register to commit (but could follow as uncommitted users). That way, it would be more likely that the user's reputation on other sites would actually be recorded and count towards commitment scores.
Another useful response would be to match against email addresses and merge accounts more automatically. I do not know of anyone who wanted to keep their Area 51 involvement separate from their StackExchange profile, and yet used the same email address for both.
I know this has come up before, more than once in fact, but I don't think this is a dupe of those questions, because it is different users this time.
Proposal: Mathematica
"you can just flag one of the posts by either account and leave us a message"(and, if not applicable, possibly flag the proposal itself and reference both users in the message). And yes, there are a few cases of this, but not sure if it's actually a big problem. Even if it's 10% of all commits (which seems high to me), that's still 90% legitimate commits. And if the user has a massive amount of reputation, he/she will probably know how to commit correctly.