dks or razer rappy tappy or macro, set the binds to release the other keys when they actuate. it is bannable, using any of the above things.
tapping in a way that you release the other key before pressing the second is allowed/not bannable. you can have 10x binds this way but you have to release the other key before pressing another.
i'd suggest you copy your osu folder and disable network access for that folder/osu! exe to create an offline osu!. then set the keybinds to other keys on that one. create a profile on keyboard/macro software for only those keybinds. leave "online" osu folder to use other keybinds.
you can't accidentally use the keybinds online that way.
E: there could be a bit complicated way to make use any combination of keys (including 3 keys) to tap with 2 inputs, if you have a macro that changes the keybinds on key release. The macro would never send inputs, you would just rebind other keys to input1 or input2 depending on which input is currently actuated. this would let you alternate using zx, zc or xc without changing settings. You could also tap using as many keys as you want, but any time you have 2 keys down, you can't use a third one (you would be holding one input twice). tldr - on releasing a key, rebind all keys (except other keys that are held down) to input1/input2, depending on which is free (the one that was released should be free).
it could be useful to add an error sound whenever you press 3 keys down at once to learn to not do that.
avoid in macro: any key release or actuation, rebinding actuated keys.
macro would do: rebind keys you aren't pressing, play a sound.
is it bannable? idk, it shouldn't be imo
e2:
these 3 things on top of normal key actuation should work:
1. on first keypress (no other key is held), bind all other keys to the other input.
2. on releasing a key while other key(s) is held: bind all other than the held key to the input that was released.
3. when actuating a third key: error sound (you wanna know)
if you manage to implement it can you hmu, i would like to use it too