Credit note number changed to original invoice number - by some program

incredible bug, we printed credit notes but at one moment some programm has
changed document numbers in  SIH, SIL, RAR, RTX files

we found huge problem in data linked to invoicing - all files SIH, SIL,
RAR, RTX concerned. We use separate document sequence for invoices and
credit notes. I have many credit notes printed on paper with correct
number, but when I look in SIL, SIH etc the records do not exists, there
are duplications of records of original invoice. Also when I look to backup
the records had correct number but every time changed to original invoice
numbers - which programs update SIL, SIH, RAR files. How can this happen. I
am completely lost in searching the source of problem, this has never
happened before also any SQL was not used.

did someone met the same problem?

Have a nice day

Michal