If we update key types from core, and groups 2 - n have a canonical type but
the same symbols as the explicit type of group 1, assume that it was a core
sym duplication according to Section 12.4 of the XKB Protocol Spec.
Ignore the canonical types and pretend there's only one group for the key -
with the explicit key type.

The protocol spec does not cover this case, so we have to guess here.