I've found two occurence of what you are looking for:
HKEY_CURRENT_USER\Software\Lachmann\MLCad\GroupDefs
HKEY_USERS\S-1-5-21-3369456988-2834548598-986560021-1002\Software\Lachmann\MLCad\GroupDefs
Currently both seems to be identical.
Edit:
I changed a bit in the registry and started MLCad. The changes has been available.
Then I clicked by error or "default".
Both entries are still the same, but I see only the default.
I can not see any flag that results in this behaviour.
HKEY_CURRENT_USER\Software\Lachmann\MLCad\GroupDefs
HKEY_USERS\S-1-5-21-3369456988-2834548598-986560021-1002\Software\Lachmann\MLCad\GroupDefs
Currently both seems to be identical.
Edit:
I changed a bit in the registry and started MLCad. The changes has been available.
Then I clicked by error or "default".
Both entries are still the same, but I see only the default.
I can not see any flag that results in this behaviour.