I have applying transaction log backups in a database with File=x and
Standby options.
Example:

   RESTORE LOG COMERCIAL
    FROM  DMPComercialLog991115
    WITH FILE=1,
    STANDBY = 'E:\DAT\COMERCIALLOG_UNDO.LDF'

   where:
              FILE=1   - Is the sequence from backup logs named
DMPComercialLog991115.

              STANDBY = 'E:\DAT\COMERCIALLOG_UNDO.LDF'  is the UNDO file

  When i am aplying transaction logs and for mistake  reaplying the same
transaction log backup, not message return with error.  the question is:  Is
the database in  consistent state after this?

Thank you in Advance
Alonso Duarte