Splitting and merging of file using sort

Hi,I have a file which contains 3 types of transactions with account number,transaction type and transaction creation date.The transaction types are 35,39 and 41.The file has duplicate records for all transactions(ie 2 records for each account number for each transaction).Now I need to remove the duplicate for the 39 type transaction alone and keep the remaining.That is only for the transaction type 39 the duplicate record(record with old transaction date) need to be removed and for the remaining transactions the duplicates need to be there.How to achieve this in a single sort step?