I have never seen one in 06 but have seen several in....8mm Mauser, 444 Marlin, .405 Winchester, 45/70 and a few others that I can't remember. Regulation would be a bugger. To do it right one should remove the ribs, put try blocks at the muzzles, test fire and adjust try blocks till it is regulated, solder ribs back on and test to see if anything changed for the worse. Then install sights and get them right in relation to where the barrels shoot. Often more man hours involved in regulating than all of the rest of the gun's manufacture.
Most were on quite old but post damascus guns.
And they have been gawdawfull heavy.
That's why good doubles and drillings are pricey.
Sam