No its not a bug, shhh don't say that too loud you'll wake them up
The stereo chorus in Guts mdulates frequencies around the stereo spectrum. I actually was'nt gonna call that a chorus, more a stereo frequency rotator type of thing. It can put a certain frequency in a spot in the stereo spectrum.
One of the by products of it is a chorus like effect. But I did'nt want to name it something that people would'nt understand so I called it a chorus. Hope that clears things up. You may even loose the chorus alltogether when you record in Mono. Be interesting to see what happens there. Something I didn't try.
Incidentally, that effect, the "chorus" type thing, is going to be part of a mastering suite I am working on. I want to use it to allow you to pan your instruments by Frequency. Just another experiment, but may turn out to be cool. I say pan but really what I want it to do is allow you to have a greater separatation between different instruments. Which is always a problem in mixing.
The idea is this, just to go a little further. You would add this effect and send multiple tracks to it. Then each track would have a frequency knob and frequency gain +/- 30db. It would also have a pan knob. Then you would select the frequencies for each track, and then pan them wherever you want. It would also blend with a dry mix as well so it could be as subtle or as enhanced as you want.