For anyone unfamiliar with it, there's a skinny captive spring that's permanenty attached to the guide rod assembly, and a regular non-captive spring on the outside. A typical Gov't Model spring is only 16 pounds and these two combined are a lot stiffer. If they used one spring instead of two it would be too stiff to work the action by hand.
I bought a spare for my P10 and haven't switched it yet. It's holding up a lot better than I thought it would. When I got my 12.45 LDA it was having some malfunctions. One of the things they did was switch from a Officer's ACP type single spring system to a Warthog type dual spring. The only difference from the P10/Warthog is that it's made for a 3.5" barrel. Brownells has both sizes, page 494 and 495 of the newest catalog, and they're in stock.
199-000-118 Recoil Spring Assembly, Blue $27.18 for 3" Barrel
199-000-352 Recoil Spring Assembly, 3.5" Barrel $27.18