Got an ancient database from fb 1.5 and converted to 2.5.
When testing it I've found "duplicated" EXECUTE_STATEMENT_FINISH being the second one a FAILED.
Than I discovered later the "duplicated" it's not duplicated at all, it happens after fetching [all] records. The thing is, there's no EXCEPTION or ERROR at all, nor executing the statement neither fetching records. The tables and data seems to be just fine.
So, why the "failed" message?
I've created a new database with only one table with the same structure and data of one of the "troubled" tables and I'm attaching so you can reproduce this behavior.
STEPS TO REPRODUCE:
1) download the attached zip and extract the db file
2) create an alias pointing to the db file and setup audit on it on you fbtrace.conf file
3) attach to the alias using a preffered client (I've tested using ISQL and FlameRobin)
4) execute a simple "SELECT * FROM CONFIGURACOES_SIG"
5) make sure you FETCH ALL records and commit
6) look at your audit log file