I have an A10 that both screen and magazine broke, and i sent it to someone to fix the screen and magazine, after it's back i couldn't play games/drag apps normally at all, like it allowed 1 touch at a time but when i used a multitouch tester it allowed 5 touches. (note: the screen/magazine were not the original since it was for 500, and the original was for 750, is it because the screen wasn't original? and is there a way for me to fix it without changing the screen?)
It would be best to bring the devices to a Samsung Service Center to have the devices checked out.
Check out this link for more details https://www.samsung.com/ae/support/service-center/
Same goes for me when I do the test I can use 5 fingers bur in games I can't even use 2 ate the same time