The proper name for this type safety is "BARRED SAFETY" and is so the rifle can be carried with the chambers loaded and safety on, with the barr in the position you see it in the picture, the safety cannot be accidently pushed to the fire position! The thin lever is clicked to the left, allowing the safety to operate normally.

The thing below the doll's head is the rib extention with a third bite called a "SCREW GRIP", and is engaged by an extention on the nose of the top lever,that actually pulls the doll's head tighter in it's socket, and acts as a block to the barrels opening, in addtion to the under luggs on the barrel lumps!

I would not disable the barr! It is a very positive feature on the rifle! I have a Westley Richards 500/450#1 Express double with this feature, and when letting a tracker carry your rifle the barr is a handy hedge against his pushing the safety to fire position! The barr has very positive click that takes some effort to engage, and dis engage, so is not prone to be accidently barred! I wish every double rifle I own had this feature!