When multiple device trackers overlap one gets randomly selected to be on top. This can create confusion as to who is actually in that spot.
At the very least it should have the first letter of each entity with a + or & between them.
Even better would be to configure a picture per set of entities.
For example I have a device tracker for my spouse, my dog, and me. It would be nice if I am with the dog to show a picture of me walking my dog to show that clearly. Same with my spouse, and us all together.