TL;DR: Sadly that’s not possible currently, no. I can put it on the roadmap to look into, but it may have more limitations than you’d want.
Longer answers:
Right now the app is capped at 4 pedals at a time so that we don’t start dropping samples due to CPU constraints (reverb in particular is rather expensive). With two signal chains, that cap of 4 pedals would be shared across the two signal chains, so you’re looking at two pedals per input (or 3 and 1). I might be able to eke out some CPU savings by switching most pedals to mono processing when in two-chains mode, but it’s unclear how much of a win that’d be. Plus the big CPU hog is the reverb I’m using, and under the hood it’s stereo-only (obviously you can sum to mono, but my point is there’s no mono CPU savings to be had there).
And then once that’s all solved for, I’d have to rewrite how params are handled. Right now in the norns ecosystem params are for all intents and purposes a static list created at app launch time (which params even exist I mean, obviously their values are dynamic). This is one of the big reasons you can only have one copy of each pedal in the signal chain at a time today, because otherwise I’d have to make and maintain four separate params sets for each pedal (one for each slot). Going to two signal chains would have the same problem 
So yeah, it’d be possible, but you’d still have at most four pedals total across the two chains, and there could only be at most one copy of each pedal across both chains. There may be some ways around those problems, but… 