Notes with prefix FF appear to be printed on a different substrate than notes with prefix FC, although both are dated 2016 with the same signatures. Clearly the notes are not polymer, but may be composite substrate or varnished paper.
If you have any 2016-dated 50-peso dominicano notes, please compare them to other date varieties and report your findings for the various prefixes.
Courtesy of Areez Habib (www.numisdragon.com).