Info on Bianchi... seat stay "dished?" Anyone know
 

Looking at an older Bianchi... painted black vice the celeste color... And the right seat stay is curved, but the left is not.

Was this the result of an accident that the owner is not revealing or did Bianchi do something unusual and put a curve in one seat stay to accomodate the cassette spacing?

Some builders use an offset rear end to reduce wheel dish. The rear dropouts are not symmetrical, the width is std (eg 130mm) but they are 5mm or so to the right.The result looks like a car crash but is a lot stronger. The downside is that you cannot fit a std replacement wheel without redishing.
I have only heard of small UK builders doing this, esp Orbit, Pace and Roberts.

Was this ever done on a Bianchi?

Not likely.