Hi, just wanted to ask if you can assign, with external software, 2 keys for doing 1 action, like, for example, x and 0 for aim.

MrPopo333 is right. You are only allowed to use what the game itself offers. You could for example set aim to CTRL, the game doesnt know the difference between left and right CTRL so both can be used.

Then you would have 2 keys for aiming but there is a catch. In RE2 when 1 key is pressed the other key gets disabled. So you both increase the mashing but you also increase the chance of dropping your aim.

then, put in the rules, because I do this for a long time, my left shift is mapped as an 'L' and I use both as dash/cancel, I change the setup of my hands in some situations.

I'm personally ok with this and this rule is only verifiable if you play with a camera on your keyboard.

Thats what I though but wasn't sure.
I had 2 keys for aim but I changed my setup some time ago to avoid this so its ok for me.
Thanks for the answers.

as Dara said, mashing 2 keys for aim will make you miss more qs.