Rainer is correct most of the time it is disconnector related or the users finger is bumping the trigger upon recoil.
Try squeezing the trigger and holding it back do not let it reset, after the bullet hits the target release the trigger while keeping the muzzle pointed down range because it could fire upon releasing the trigger do this several times slow. If it doubles then it is trigger/hammer/disconnector related.
If it stops when the trigger is held to the rear then it could be an unintentional bump.
Hi perf barrels and bolts
8 twist, 5R, Melonite, Wylde chamber