I was wondering the same thing. I think the answer is in the
"General Rules for All ARRL Contests."
Rule 3.4 states:
"The same station may be worked only once per band
for contest credit."
This tells me that we cannot work a station on PSK31 and RTTY
on the same band. I cannot find a statement in the ARRL HF contest
rules or RTTY Roundup rules overriding the general contest rules,
so it appears to me that 3.4 stands in the RTTY Roundup.
Good luck in the RTTY Roundup!
-Dean - N6DE
CQ-Contest on WWW: http://lists.contesting.com/_cq-contest/
Administrative requests: cq-contest-REQUEST@contesting.com