Client Tools :: Logon Trigger Creates 2 Records?

why my logon trigger always creates 2 records with different timestamp. Also is this the proper way of excepting records to insert?

Script.

CREATE OR REPLACE TRIGGER TR_LOGON_AUDIT
AFTER LOGON ON DATABASE
BEGIN
If user<> 'DBSNMP' then -- don't want to insert this
if user <> 'SYS' then -- don't want to insert this

[code]....

Result when select.

OS_USERNAME LOGON_TIMESTAMP
----------- ----------------
GAN 2010-08-05 14:27:52
GAN 2010-08-05 14:27:55