Is there any oversight to stop duplication of cemeteries? No
And is there any other way for members to contact find a grave to get it fixed - Yes, see below
I can't log into the forums when I try it tells me they have no member with the id or password (I have it written down) - Your forum ID/password is different than that for the main site. Sounds like you need to register as a new forum user.
and it says NON MEMBERS can contact
cemetery@findagrave.com? - No. Use the "info@findagrave" email address for general questions/problems such as this.