I had dual pistol crosshair on and wanted to turn it off without turning the main crosshair off, but it didn't work. If you have the main crosshair on you can't turn off any other crosshairs, they will be the default crosshair if turned off. In the same manner, if you turn off the main crosshair, all other crosshairs will be turned off too, and you wouldn't be able to turn them on without turning the main crosshair on first. Also, if you don't have the main crosshair turned on, you can't see the hacking timer and use icon either. It seems to all be connected with it.