Summary: When Villagers have to open two consecutive doors with one door in front of the other or when there is a carpet behind a door, the Villager will open the first door to get between the two doors or to get inside if there is one door, then after the villager gets in between the two doors or the door and the carpet, it continuously opens and closes the first door instead of opening the second door / walking on the carpet and getting inside the house.

From MC-94484: This might be attributed to the fact that Villagers think the second door is an obstruction, as if the door would be an actual block preventing Villager's movement, even though it clearly can open the second door.

From MC-97799: As the Villager's height (1.95 blocks) and the carpet's height (0.06250 blocks) combined is over 2 blocks, the Villager should ignore these invalid houses, because it's pointless for the Villager to attempt to get inside, seeing that the Villager can't get through.

To Reproduce:
1. Create a house that is valid. I recommend two block thick walls, but one block thick walls also works.
2. Place two doors with one in front of the other, make sure that the outer door is touching the walls, or a carpet behind one door.
3. Spawn a Villager.
4. Set the time to night. This encourages the Villager to enter the house.
5. Notice the behavior of the Villager towards this. The villager should open the second door, but treats it as an obstruction, for the carpet, the Villager should ignore the house.
6. If it is escaping the Zombie, as shown in the screenshots, the Zombie will attack the Villager, even through closed doors, and the Villager dies, which the Zombie attacking through the door itself is another bug. See MC-2310 for more.