As Thomas says, Mach or CSMIO does not care whether you have a single switch for + and - limits. On my Chiron it has a single switch on X, one on Y and one on Z. They are all linked in series (Normally closed switches) and if I hit a limit the machine stops.
Sounds to me like your Home switch is too close to your limit switch for the speed you are homing at AND the acceleration set in Motor Tuning. In other words the axes can not decelerate in the distance required before it hits the limit switch.
You have 2 options, actually 3. Reduce the homing speed, increase the acceleration or move the Home switch trigger further away from the Limit switch trigger.
Looking at the wiring Thomas posted it looks like the Limits are Normally Open, that is not really a good thing, much better if they are Normally Closed.
If they were Normally Closed then you could also have a momentary switch on your panel as an override so that if you hit a limit you can press and hold that switch and it will allow you to Reset Mach and jog off the limit.
Hood