I checked it and the code comes from other issue:
It is probably this is valid on 1.1.x branch (due to its inner portlet code).
This was a hack that comes from pre portlet-bridge times (note in that time the solution for portlets was use myfaces and its custom generic portlet). In portlet-bridge, the portlet specific UIViewRoot implements NamingContainer, so its clientId is appended to all generated ids implicitly.
You're right, Michael, this issue should be fixed on 1.2.x and 2.0.x branches (I think there are some code in tomahawk that requires it too). I'll close
MYFACES-702 and MYFACES-454.