Hi Brent,
You hit the jackpot with this find. This is (albeit a tad worn/polished) the rare bronze officers variant, die cast, not struck, hence the odd characteristics on the back. When issued this would have a been a beautiful dark chocolate brown. Still a very nice badge, if you're looking to get rid of it I'd be glad to give it a home.
At the recent Kangaroo reunion, Lt. Harry Tatchell was wearing his bronze badge on his blazer lapel and his Brass badge on his beret.
What part of the country are you in? A great find. You should ask the antique dealer if there is any other items that go with this badge (like the collars!)
Bill.