Yes, a squib load could have left a bullet lodged in the bore and the next round shot them both out. Since the split is at the end, I'd guess that the stuck bullet was near the very end of the barrel. For barrel obstructions caused by a squid load where the bullet is lodged in the middle, the next round usually caused a severe bulge, followed by the cycling slide then jamming the bulged barrel into the barrel bushing, REALLY locking things up.
Whenever the report of firing does not sound right, or there is incomplete cycling of the slide, one should stop and investigate why, and check the bore for obstructions. Also, typically handloaded ammunition voids the manufacturer's warranty so you use handloaded ammo at your own risk. Of course a squib load can happen with factory ammo but it is a rare event (except TZZ Match .45 Ball when it was first introduced into the military supply system. Their AVERAGE powder charge was ok, though!)