Not that I'm aware of but I could be wrong, I've never seen under the skirt on a screen used helmet. It does have a skirt as seen in the picture that kind of works as a chin strap though. But that is optional not everybody uses the skirt because of heat and the reduced air circulation.
The more I think about it the more I believe that Jango did not have a chin strap. It would be very difficult to fasten a chin strap with the skirt in the way, even with help. That's probably why Boba Fett did not have a helmet skirt (chin strap instead.