Linn,
As has already been said, the second name is almost certainly a
retailer.  You can check city directories to find the company and its
dates of operation but, if you have enough time, you could also
check old newspapers for advertisements.  Lehner's Encyclopedia
of US Marks on Pottery, Porcelain and Clay (1988:129) has a
"Dohrmann Hotel Supply Company"  in San Francisco filing for use
of the mark "DOHRCO" in 1945, claiming use since March 1, 1928.
 You could contact me off list if you want me to fax this page to
you.
Meta Janowitz