Sometimes, when traveling accompanied by a tamed wolf, it teleports to keep up with the player (as it should), but instead of one, there appear two identical wolves. After that they seem to be normal and independent and don't sync back or anything, effectively duplicating the wolf, not just visually, but functionally.
I'm using a lower than average computer and the wolves lag behind a lot, so it might have to do with them getting very far in space and sincronization steps. It happens more often when running long distances.