They will clash unless you control when they run. Shut off one, to run the other that conflicts. I use Malwarebytes, Avast,CC Cleaner and Windows Defender - in a kind of rotation. They each have their value, but CANNOT run at the same time. CC Cleaner stays on. Malwarebytes and Avast seem to clash - so I manually run one, then the other - and Defender also sometimes contributes to the battle. So periodically - once every few days, or once a week, I switch them. If you FORGET - you might find that a valuable one has been automatically switched off- or the clashes will make themselves apparent. I too would welcome any advice that experts woudl share about this - EACH of these find something each time, that the others missed, so that is why I go thru this.