As adverbs the difference between dually and ducally
is that dually is in a dual manner; doubly while ducally is in the manner of a duke; in a way that befits a duke.
dually
English
Adverb
(-)
In a dual manner; doubly
ducally
English
Adverb
(
en adverb)
In the manner of a duke; in a way that befits a duke.