In fact, the game has a section for two simultaneous players, and it works very well with DS, the only thing that would be needed is to add the focus function for P2
You are right Bug Buster is an arcade game and Spray Gun also. Both are similar, but not the same game
https://www.highwaygames.com/arcade-machines/spray-gun-9065/
https://www.highwaygames.com/arcade-machines/bug-busters-8177/
Yes, I´m using sinden, but I think the problem is that if you use the control option to "emulate" the left thumb, the absolute coordinates don´t work anymore