I have an avocado tree I inherited from a former coworker and knowing nothing about indoor avocado trees, I did some reading. From your article, I'm thinking this might be one of the tree suckers you mentioned, but I don't want to start clipping things off and inadvertently killing this plant. I've attached some photos. Thanks! (I know it's not in the best spot right now, but it's only been there since this morning. The tree is going home with me tonight to a window with lots of sunlight.)
Is This a Tree Sucker?
Certified GKH Gardening Expert
This could be a tree sucker or simply a tree that's developing two trunks, but it could also be a grafted tree. If possible, it would be good to get some clarification from your former co-worker on whether this is grafted.
The two stems look about equal in size, and I'm not sure which of the two stems (or both) would be the grafted one, so I think it's best to leave both of them on.