Unless you use an electronic crossover that provides multiple outputs to multiple amplifiers all you accomplish is additional power. Is that what is needed?
If so, then the issue for not idential amps is Gain. If one amp has a gain of say 26dbl, and the other 30dbl, then you lose seamlessness of integration of frequency range of the different drivers.
If say the 30dbl gain amp is connected to the tweeters then you have essentially 'turned up' the treble, or vise versa, if you see what I mean.
If you do need more watts of power to drive your speakers and you have an extra amp (with the same gain) you want to use instead of upgrading to an amp with appropriate power, then intall a splitter cable between the preamp and the amp. Then one spker cable to treble, and the other to bass.
You now have four amps driving your speakers instead of (stereo) two. Add up the watts and especially be careful its not too much even if the one amp is below, or close to the minimum specified by the mfgr. You can contact them to find out the power recommendation if not in the manual.
You an see its a lot of trouble and expense if you do not need more power, and nothing is really gained if you do not.