It's not the same as 'bump firing'. It's doubling caused by not following through on the shot. You release the trigger too soon and the recoil causes your finger to hit the trigger again. It usually only happens when shooting from a bench. A match grade trigger can escalate the frequency. It's not particularly dangerous, but it certainly is exciting.
While it can happen with any semi-auto, it happens more often with M1A's due to the relatively lighter triggers. The first stage of an M1A trigger isn't long either. About 1/8". Other semi-autos with two stage triggers, like an M1, have a heavier and longer first stage take up.
You don't need to change any parts. Just hold the rifle tighter into your shoulder and the trigger back until the rifle is finished recoiling.
What's 'bump firiing, you say? That's putting your finger into the trigger guard sideways and rapidly hitting the trigger to pretend you have FA. It's daft and not safe. You have no control over where the bullets go.