Different masks on one layer?

Earlier I used two different layers, one animating only right arm and other animating both arms, but I decided to use only one layer (Animator became very clunky and switching animations was very difficult) and came up with this:


(I am using "Override" mode)
Blue ones use only one hand, red uses two
As expected, reload works perfectly fine, but one-hand animations look like this:



How do I prevent right-hand animations to override other hand if it's not needed?

(yes my English is bad cuz it's not my native language. I'm kinda stressed about it so I'm writing it at the end)