Clicking left stick in also clicks right stick?

Kind of a bizarre issue I'm having, but I have a controller where if I click the left stick in it also sometimes registers the right stick being clicked in at the same time. I first noticed it in call of duty when I kept trying to sprint but would crouch or go prone instead. Tested it on PC using the wireless receiver and a controller tester and it does indeed show up as the right stick being clicked in occasionally. I've taken it apart already and given everything a good clean but it's still happening, any ideas on what could cause something like this? I realise it's a pretty weird issue but if anyone has any advice it would be helpful, thanks :)