My wife has 2 different Apple IDs. Her old Apple ID is on her old iPhone 5s’ and iPods and her new Apple ID is on her iPhone 8.
Because I have both Apple IDs saved to the same contact, all of her devices ring when I FaceTime her. It never really asks me which one I wanted to call, it just goes with whichever answers.
Could it be that someone who has your work Apple ID also has your personal Apple ID?
You can always disable how people can reach you in FaceTime by going to Settings > FaceTime and unchecking your Apple ID from “You can be reached by FaceTime at”.
However, if they have your work and personal number saved to the same contact, it’ll still happen.