Confirmed for teleporting wizzrobes and Gleeok heads (for NES dungeon rooms). They can basically go into walls where there is a doorway. Wizzrobes can also appear 1-tile deep into walls.

Doesn't happen with one of my older dev builds, which probably means it was a small change right around 2.5, or slightly before. (I did not label it by revision unfortunately.)

Not really sure why.