Your theory of a choke just ahead of a choke has already been marketed. It's not a jug choke ahead of choke, but it is "two in one". It's called the Brain Choke (ironic, eh?). You can read all about it here.

https://brainchokes.com/en/inner-profile/

Note the street address (color added)


42A Tzavella str, N. Psychiko
P.O. 15451, Athens Greece

I wanted to say, you can't make this stuff up, but somebody did. That said, if someone would donate me a choke tube to fit one of my shotties I will be happy to do an impartial test on my plate. After all, they were only looking for the same thing we all would like to have ...............equal density from edge to center to edge. Holy grail, indeed!

SRH

May God bless America and those who defend her.