A lot of girls cover their heads during the Azan with a dupatta, but I don’t know if that is a cultural thing or a religious requirement. They only cover a portion of their heads though. It looks like they are only trying to cover the back of their head! Some girls wear the dupatta on their head habitually, but again, they reveal more hair than they conceal. The dupatta looks like it will slide off any second!
I think the dupatta was generally designed to be worn to cover the…ahem, but a lot of girls wear it around their necks. It has turned into a fashion accessory rather than a requirement. For others, it is purely cultural.
Even while covering the head during the Azan, the dupatta must still be covering the…you know what. Some women cover their head during the Azan in a manner where they end up revealing what really needs to be covered.