Importing OFX statements for two accounts with the same prefix - gnucash mixes it up

[Paweł Zając]

Dear gnucash users. I have two accounts with the same 18 digits prefix.
During import of OFX statements for these accounts gnucash mixes up these
accounts, and import all transactions from two accounts into one gnucash
account. Why is that so? Does gnucash recongnize only a short prefix of
account number? My account numbers are in IBAN standard.