Over the past couple months Disqus community has been growing; Some of these sites use their own logins in conjunction with Disqus, which may mean that commenters end up with multiple profiles. Multiple profiles can also occur if you choose to comment on Disqus-enabled sites with different authentication choices (eg. Facebook or Twitter), or even comment as a guest.
Disqus now made this manageable with "option to merge" your multiple profiles. You can find this in "Edit profile" box (link next to your name near the comment box). Choose to merge all comments associated with your email address with just a couple clicks.
Also, last week, Disqus launched new community profiles, that help you bring up anyone's profile anywhere on Disqus — just clicking avatar and a small box will pop open. If you're viewing someone's profile, and they happen to have a green sash, that means that they're a moderator of the site.