I don't know much about Crested Ducks if that's what you are referring to. The Romans have a cap sometimes called capped or tufted as I understand. The ducks I've seen are called crested with a right to left centurion type of crest.
A few dream cross breeds of mine (presently):
Giant African Dewlap / Tula Fighting Goose
Roman Tufted / White Embden (the order is pending)
Roman Tufted / White Embden (Offspring) / Steinbacher Fighting Goose
Anyone else working on the crossing of geese breeds or letting it naturally happen...