These Coro cockatoos have been hand painted with enamel. At the center of each flower is a faceted, faux diamond.
As you can see by the patent below, this duette was designed by Gene Verrechio and patented in 1941. Pat # for the duette is Des. 126,490 and for the clip #1798867.
Coro invented the "Duette" in the 1930s. An ingenious invention. The design involves two pin clips that fit together, joined by a mechanism at the back, so they can be worn together as a single brooch. Or, you can take them apart, and wear them separately.
Reference: Fun Jewelry by Nancy Schiffer. p142.
Reference: American Costume Jewelry by Brunialti & Brunialti, p. 57,58