Tamed wolf has merged with untamed wolf.

I have a wolf that I spawned in using Creative and tamed. It spawned in with an untamed wolf on top. When I push them, they are both moved. The untamed wolf appears to not be able to move, as it tried to hunt a sheep and could not move the tamed wolf it was on top of. However, its appearance did change when it sighted the sheep.

Steps to Reproduce:
I spawned the wolf, and it already had the other wolf 'fused' with it. However, they were in the same position, so I didn't notice. I then tamed one out of the two wolves. (I spawned this wolf using a Wolf Spawn Egg.)

Observed Results:
If I attached a lead to the two wolves, only one had to be attached in order for the pair to move in perfect unison except for the direction they face. The wolf that was not tamed could change its sprite to redder eyes when it sighted a sheep, but it could not be interacted in most ways, such as tamed. If the tamed wolf sat down, as shown in the image, the untamed wolf would not. I did not attempt to nametag either of the wolves, armour them, or dye the collar. There were multiple other wolves spawned in close proximity at the time. I am sure that I did not accidentally spawn them both in at the same time.

Expected Results:
For the issue to be resolved in perhaps a patch, or a moderator to kindly explain to me what I have done if this is not a bug.