Lam,
Sorry we hadn't gotten back to you yet. We actually did some testing and code checking for this usage scenario earlier this week, but couldn't immediately recreate the issue. We also checked the code and verified that we do not allow auto-mapping of users based on email address if that Facebook user already has a mapping on your site.
Originally, we thought we'd be able to narrow this down quicker. I believe we know what the issue is now, and were already planning on doing more testing tomorrow. Basically, this is a case of a user re-mapping their account (which we do allow). If you'd like to try disabling this behavior, you can do so by modifying the /components/com_jfbconnect/controller.php file. At approximately line 84, you'll see the following block of code:
else #User already logged into Facebook. Update their Facebook mapping
{
if ($usermapModel->mapUser($fbUserId))
...
...
}
Comment out (put a //) all of those lines from the else down to the } (about 7 lines total). Again, we're planning testing soon, but if you try it out, and it fixes your problem, we'd love to know your results.
Thanks,
Alex