Enabling TMS for a class initializes the Equality Key (as STATED - otherwise the TMS would have been enabled before) for all instances of that class. This behavior, however, overrides the Key of any instance of a subclass which has a dedicated OTN, on which the TMS has been enabled
Fixed by https://github.com/droolsjbpm/drools/commit/b3b02e659
Verified with BRMS 6.0.1-redhat-2