[T. O'Heir]

Being a pair of flintlocks doesn't make 'em dueling pistols. Those came in boxes and were literally matched sets.
Nor does 'old' equal 'collector piece'. Copies of flintlock and percussion lock pistols are everywhere. It's entirely possible the percussion "pocket" pistol is more valuable.
Who made 'em and where, matters. (Can't make out the name from your picture.) Isn't really possible to put a value on anything from a picture. She needs an expert.