I tried to import a database dump (exported with ddlutils) back to the same database system (SapDB).
In this process i got a lot of warnings like
28.02.2007 14:07:54 org.apache.ddlutils.platform.PlatformImplBase executeBatch
WARNUNG: Attempted to insert 2 rows into table MYTABLE but changed -4 rows
Looking at the source code (PlatformImplBase.executeBatch) i found out that SapDB returns 'Statement.SUCCESS_NO_INFO' as result of 'statement.executeBatch'.
Since SUCCESS_NO_INFO is defined as integer value -2 the method adds -2 for every successfull statement. So having two insert statements results in -4 which is definitely not 2 and the warning arises.
I got the same effect with Oracle 8 so i didn't try other databases and assume that this is a general problem.