Robert Gowans

I was checking my HMRC app recently and noticed that there are two entries for income payment from my work for the same amount in October. Both payments are individually correct in what I normally receive. I have checked my bank account and I have received only a single payment for the correct amount in October as expected and there is no duplicate payment. My question is how did this happen and who is responsible for sorting it out as it will impact my personal tax allowance since the tax office may think I am earning more than I actually am! Thanks Robert