TWo mono amps, or a stereo amp that consists of two highly isolated mono amps in a single box even, may well have better channel separation and less crosstalk, which could work in favor of a more "holographic" presentation, but whether or not this would be heard in comparison to something else or not would still depend.
Assuming quality gear designed well in all cases, using two mono amps is probably a good insurance policy that overall performance of each is fairly independently optimized which should always work in ones favor.
In a nutshell, more can be done better with a single self contained monoblock, with dedicated power supply, etc., than can be done for similar cost otherwise.