Infinite pig guards in a single tower?!

In this bug we see an infinite amount of pig guards crammed into a single tower. They are surely squishy.

In Hamlet dlc, there are pig guard towers. Each tower will always have a pig guard patrolling around it. 

If you kill that patrolling guard and wreck the tower with an ordinary hammer, another pig guard will spawn out from the rubble.

Then you can kill the new guard, repair the tower with the hammer, smash it to rubble again, a new guard spawns, kill the guard...

This can be repeated infinitely.

And a new guard will also spawn if the tower is permanently destroyed with the executive hammer. The guard will spawn from the tower's loot.

After some testing done by myself, it seems this bug does not happen if you destroy the tower with a deconstructive staff.

This bug doesn't seem to occur if the tower already has 1 guard on the outside.