The cop from Die Hard and the one from Family Matters aren’t just the same actor, they’re the same character in alternate universes*. In one universe, the cop shoots a kid, switches to desk duty but then learns to kill again in time to save John McClane’s life, and thus Christmas, from the Germans. In the other, he doesn’t shoot that kid.
That kid was Urkel.
Sliding doors, man.
*Of course their names are different – they’re in alternate universes. Stop looking at me like that.