Feather Duster Question

Sorry, I'm hooked on feather dusters. I just bought another at my LFS.
They did not know what kind and it really didn't matter to me. I wanted
it!! It's mahogany in color and the crown is more like a pom-pom than like
the crown on my Hawaiian feather duster. Imagine my surprise when out
popped a different crown from the opposite end. It has a totally different
look and is lighter than its tube mate but darker than my Hawaiian and is
shaped more like the Hawaiian.. Ok, the question is, how many worms and how
many species can live in a single tube? Been googling to find out what kind
it is.
--
Ann R