In the new 2019 version just released, have a look at the tutorial on “replays” linked from Character Animator Tutorial Videos . You can set up a scene for shooting both guns, then record that as a reply so you can click a single button and have it do the shoot sequence.
You can record the take for one arm, then go back and record the take for the second arm - just drag the playhead back and record a second one. There is a little example in this video: Project Wookie, Episode 3: Recording a First Scene - YouTube - if you don’t want to watch it all, skip to 4:30 in (but video has a few different tips like renaming your draggers).
You can also do clever things like if you *always* want to move the draggers together, you can put an invisible rectangle to join the two arms and put a dragger on that. But “replays” sound more like what you want. Then you can shoot alternating hands for example.