try an action of the type "Guess value" (import tag fields)
Source: $regexp(%artist%==%title%,(.*?) & (.*)==(.*),$1==$3 \(& $2))
Target: %artist%==%title%
For
You could do something similar with the comma instead of the & - but what "Earth, Wind & Fire", "Bell, Book & Candle", "KC & The Sunshine Band", "Kid Creole & THe Coconuts" and many more?