Connect By Prior

Hi,

I am trying to use connect by prior in hierarchical query. I am able to =
view all parents with their children in a certain format but I am also =
getting all the records one more time and couldn't figure why. The =
statement I am using is

 SELECT ID
 ,LPAD('-',2*(LEVEL-1)) ||OPT_DESC AS OPT_DESC
 , PARENT_ID,LEVEL
 FROM SCS_MENU_OPTION
 WHERE ISSHOWN =3D 1
    CONNECT BY PRIOR ID =3D PARENT_ID

If I used start with, I get only one sub child record and its sub =
children. The information in the table can be illustrated as below:

--parent 1
      -- child 1
      --child 2
            -- child 1
--parent 2
      -- child 1
            -- child 1
            -- child 2
      -- child 2