Hi again Bob-

I don't shoot an eleven bore rifle.
I do however have a couple of black powder sixteen bore cartridge double rifles that I load with roundball, the powder charge tends to be around 2-3/4 drams of FFg for the lighter loaded one, the heavier of the two double rifles will take over three drams and the same roundball (.666"dia)
Both of my rifles are damascus tubed guns by the way.

At first the symptom you speak of there, 2-1/2 drams of powder crossing the shots, 3 drams crossing even more might have one thinking that less powder would be the answer.
My instinct here is to ask what your chronograph said about it all.
What was the velocity of either of those loads?
If you're in a -waaay too low velocity- range, you might need to step things up a bit to get the gun to push enough (interior ballsitics-wise) to get it to uncross.
Might need more bullet too.

What does your rifle weigh?
That and the bore/groove measurements, as well as rifling rate might give us some clues here.

--Tinker