Eunice two step isn't the only song like that. I've noticed that on more than one song. Lacassine for one. Accordion usually plays the B but not fiddle. And that turn is as easy as they come.
I need to listen to Eunice two step again. I always meant to learn it but never did. I'll let you know about the turn.
Z

It seems most versions don't have the fiddle doing the b part

here are some exceptions

Paul Daigle and Savoir Faire

Trio Cadien
(Menard/Lejeune/Smith)

Savoy-Doucet Cajun Band
Live at the Dance

Mark

If I recall, Mike Doucet does it on one of the
Doucet/Savoy albums I have...

The reason you never really hear fiddle do the turn on the Eunice two step is because it sounds to dang good compared to the way the accordion does it
John

see Neal's site, hadacol it something, Floyd LeBlanc does a fiddle version of the song. (Look quick in case it's one of the ones Neal hasta take off of there.