More than one user is being mapped to user <name>. Only one user can be merged with a user in the domain. Correct user <name> and try again.
When you upgrade users in the repository, you are trying to map multiple users in the selected domain to a single user in the PowerCenter domain. For example, you cannot map users “RSmith” and “rsmith” in the selected domain to user “RSmith” in the PowerCenter domain. In the PowerCenter domain, user names are not case sensitive.
Rename the user in the selected domain or merge one of the users in the selected domain with a different user in the PowerCenter domain.