What I expected to happen was...:
I was taming a dog, when i got 2 achievements, one which seemed like the wrong one.

What actually happened was...:
i got the "A Complete Catalog" achievement, which is for taming all types of cats. in this world i had no prior actions with cats, and only this one dog.

Steps to Reproduce:
1. get a new world

2. tame a dog

3. you get 2 achievements

below, you will find a video on the topic. it displays the bug in action.