UTR Number Changed without my knowing

Ive been self employed for nearly 20 years with same UTR and no problem doing my accounts every year and then this week i get a letter to state i havent completed 2021s online accounts. I have completed and I have them printed and saved, The letter today says I am using an old UTR number and states my UTR and some other UTR number I have never heard of before? I am baffled as I have paid my taxes etc for this year and every year with my same UTR and have never heard of this other one? Is this a scam of some sort??

Hi,

You will need to contact HMRC to check why there are 2 UTR's set up for you. You can contact our Self Assessment team below.

Self Assessment: general enquiries

Thank you.