Theoretically this is possible, yes.
You would have to double the
$replace and compare the outcome like this
The logic behind this complicated Format string is:
a) Check if the current content in %ARTIST% is NOT the same as the outcome of the first
As @ohrenkino wrote, if there is no match in the first
$replace(...), the content of ARTIST will be filled into GENRE.
b) If the condition in a) is TRUE (= the ARTIST is NOT the same as the content of GENRE = the GENRE would be replaced) then execute the second
$replace(...). This second $replace will replace the genre with the text you set here.
c) If the condition in a) is FALSE, then leave the GENRE untouched
As you can see, this becomes practically unusable, because you always have to adjust the Artist & Genre pairs in both
If you imagine that you want to be sure to find "ACDC", "AC/DC", "AC-DC", "AC🗲DC" and all the other thinkable variations to replace the genre with "Hard Rock" (or is it "Bluesrock" or "Rock 'n' Roll"?), I can not seriously suggest to go this way.