the bug is that if you replace the bed (on the same block or another without no difference) the villagers will spawn to one more villager as if there are two beds, and this results in homeless villagers who are pretty dangerous. at night they go to other villagers houses and commonly lefting the doors open.about the picture, i created a small perfect village to reproduce that bug. the black dots are houses where i replaced the bed. oh and also if you kill the hobos the will spawn them again