The Pathfinder core rulebook has this to say about Light Crossbows:
"Normally, operating a light crossbow requires two hands. However, you can shoot, but not load, a light crossbow with one hand at a –2 penalty on attack rolls. You can shoot a light crossbow with each hand, but you take a penalty on attack rolls as if attacking with two light weapons. This penalty is cumulative with the penalty for one-handed firing."
This is particularly relevant to Shadowshooting weapons, since one can actually dual-wield Light Crossbows in that circumstance.
This sounds like a circumstantial situation and not something I’m going to code change for the time where you get a round or two of two weapon crossbow firings. As such, this seems to be more a rule you would add to the description displayed for the weapon and not just allow two light crossbows to be wielded (Just an FYI, you can treat weapons “Carried” as equipped for the same effect).
What would be the reaction to a community member opening a PR with the code change, out of possibly-non-idle curiosity? Fixing a corner case that nobody else cares about is the greatest of Open Source traditions, I believe, and I might partake if it’s welcome.
Anyone is welcome to contribute. I’m just not going to be that person. I have conversion to a new system to convert to and this is a very extreme corner case where it’s like a single round option, unless you have an option that allows for never needing to reload… You’re talking about changing the HANDS rules for the Light Crossbow, adding a conditional rules, and then opening us up to false bug reports from the community when they equip said crossbow when they get penalties…