Double tap isn't military. Originated with IPSC and self defence with handguns. Equates to "stopping power", where the relative stopping power of calibres were compared, with the conclusion that you should fire two shots if you want to stop an assailant. One shot is good by two are much better, without wasting ammo.

Spilled over from the sport I presume.

In contrast to military, where rifles, space and distance from the enemy are the norm. Stopping an assailant in your home isn't a military issue. You just use more machine guns and mortars and artillery, etc.