Is there a way to copy muscle weights from one muscle system to another, same like copying painted skin weights ?

I have a problem, I didn't notice two vortex points that had to be merged first before skinning and all that.
I merged them now, it worked, however when deleting non-deformer history I'm getting vortex "spikes" (weight re-calculates badly).

I also tried duplicating model, copying painted skin weights, which works. Then I saved muscle weights from original muscle system to a file and loaded them to a new duplicated muscle system - which also gives vortex "spikes".

Any ideas ?

Ps. I could fix them manually but it would take couple of hours.