I'm guessing from the OPs description that it's not an issue as long as they are not both sending a signal that it's two amplifiers connected in parallel and not a bi-amp setup.
I have a home theater receiver and Pathos integrated connected to my speakers in parallel, but I have an intermediate toggle switch in the speakers cables so that only one amplifier can send a signal to the speakers at any given time. The custom switch even has a resistor to provide protection during the switch since it was first used with an all tube amplifier that needed a continuous load.