What rifle would have a double trigger??
It's a reasonably common form of set trigger. One of them sets the trigger, and the other goes off when you tap it. These days, they usually work by pushing the single trigger forward to set it. This lady has excellent taste in rifles though!
Looks like either a better grade of Pre-War Mauser sporter or a rebuilt military gun judging by the trigger guard. Although the photo is not too clear it also appears to have a front scope base that was installed in a dove-tail cut in the front receiver ring. Unfortunately many scopes mounted this way had the cut made too deeply and seriously compromise the integrity of the receiver. FWIW: Many factory Mausers were done in this way but German law now forbids the practice....
They haven't twigged yet that you are referring to the beard.....
That type of trigger mechanism was often called a Stretch trigger as one had to stretch the finger to touch the front on to fire. The rear trigger sett the mechanism the front set it off.
Mauser Obendorf offered at least a couple of different types of Double sett triggers.