The ArcFM Login form may strip leading zeroes from numeric usernames. This is because numeric user names are stored of type REG_DWORD (32-bit number) in the registry.
This issue may be related to the following bug, fixed in ArcFM 10.1.1.
MM50753: ArcFM Login Form has different registry data type for numeric user names.
Bug is resolved in ArcFM 10.1.1.