in the context of higher end Home Theater multi-channel systems, more that 2 subwoofers is common place. the reason is that more than 2 subwoofers, up to 4, will even out the bass nodes in your room. and each sub is more linear than a single sub. even with only a single low frequency channel. and with movie soundtracks having so much low frequency information it’s a natural fit for that application.
there is lots of information on ways to integrate multiple subwoofers into a system out there to find. the SWARM approach is a very good one.
i have three Funk Audio 18.0 subwoofers in my Home Theater room (on a single LFE channel) and it’s awesome. and i have only level matched them so far, no fine tuning.
forget about deep bass directionality; while it exists really it’s higher frequencies that are mostly giving you directional clues. your deep bass priority should be to even it out as best you can so doubling and such is not overwhelming the music. and 3 or 4 subwoofers around your room will help with that.