Same thing happened to me about 20 years ago; nasty letter, nasty agent when I called about it.
I only asked one question; how could I, when I had a full time supervisory position in a city organization in Southern California, be working at the same time in Virginia, Ohio, Kentucky, Missouri and Minnesota?
Never heard back from that nasty lady at the IRS.
bet it’s very common
i hope your social security payments get boosted :)