As nouns the difference between dueller and duller
is that dueller is while duller is one who, or that which, dulls.
As an adjective duller is
(dull).
duller
English
Adjective
(head)
(dull)
Noun
(
en noun)
One who, or that which, dulls.
* Beaumont and Fletcher
- But, of all, your grace must fly phlebotomy, fresh pork, conger, and clarified whey: they are all dullers of the vital spirits.