Ohloh currently does not attempt to automatically tie multiple unregistered contributors together as the same contributor. This makes sense in many cases, because a simple username often does not uniquely identify a contributor.
However, I know of two cases where Ohloh can determine with reasonable certainty that multiple unregistered contributors represent the same contributor.
First, when using version control systems such as Git that include a contributor's full name and email address, it seems reasonable to assume that if two contributors have the same full name and email address (and both the full name and email address exist; don't do this for an email of <>), the two contributors almost certainly represent the same contributor.
Second, if two projects have the same enlistment, and thus the same repository, corresponding contributor names would represent the same contributor.
Copyright © 2013 Black Duck Software, Inc. and its contributors, Some Rights Reserved. Unless otherwise marked, this work is licensed under a Creative Commons Attribution 3.0 Unported License . Ohloh ® and the Ohloh logo are trademarks of Black Duck Software, Inc. in the United States and/or other jurisdictions. All other trademarks are the property of their respective holders.