Here's a picture of an edge with multiple bevels. In this case, the main bevel is 24 degrees and the secondary "relief bevel" is 18 degrees.

(borrowed from Last Visible Canary on BF)
The reason for the relief bevel is to aide in touching up the blade, should it get dull. This blade is a 1/8th" custom shop Boss Jack.

As for pros and cons, a convex edge has more metal behind it, therefore making it more durable than a standard V edge or a hollow ground edge.

Cons, at least in my experience, is it is harder for me to reshapen should the edge take a real beating compared to a V-edge with a set angle. I'm sure others who are better at sharpening than I would disagree.