RM1258 | RO instructions: Two files for same taxpayer
From HM Revenue & Customs · Repayment Claims Manual
If you find two files for the same taxpayer check and compare the files
if there are two repayments of the same tax for the same period tell your Inspector before you follow the over-repayment instructions at RM5140
if you find any other discrepancies tell your Inspector if there is no over-repayment or discrepancy, or when your Inspector has seen both files, merge the files
if there is an R299 in one file, note the R299 that the original file has been found and merged with the reconstituted file
if the files have different references, deal with as a transfer from one reference to the other.