Oracle Database Discussions

hello
im trying to set up a db trigger that will log all DDL transactions performed on the db;
for that purpose the following statement is included in the trigger to return the information about the user making the changes:

	select 
      osuser,
      machine,
      process,
      program,
      AUDSID,
      sid,
      SERIAL#
   from 
      v$session
   where 
      AUDSID=USERENV('sessionid');

problem is, this statement is returning multiple rows when 2 users are connected to the same database using the same username e.g. SYS;
i can see that audsid is identical for these 2 users, but the osuser, machine etc are different, so i can easly say which one is which;
how to distinguish these in the query to be able to capture only the one actually executing the DDL transaction?
id appreciate any tips
thanks very much
rgds