Value is an interesting concept, especially when it comes to double barrel shotguns. Why one gun is more valuable than another is sometimes hard to figure out. Here’s an an example of what I mean.
This Parker DHE side by side is online right now at Gunbroker.com:

This other Parker DHE double barrel shotgun is at Auctionarms.com:

Boths guns are pretty similiar: 12 gauge DHEs with single triggers. They’re both two barrel sets, and they’re both in excellent original condition. They even have similiar stock dimensions. So why is it that one is going to bring so much more than the other?
Their are only two big differences that I can see:
1. The DHE on Gunbroker letters as original. Of course, this is a big deal. Provable original condition is the gold-standard on old shotguns.
2. The online auction companies. Maybe Auctionarms doesn’t have the traffic that Gunbroker sees.