Isn't Alpha Phi Omega something along the same lines of Circle K International? If that were illegal I'd think a lot of us on here might be in trouble
Dual membership I think is meant to cover fraternities with 'secret' rituals (Delta Upsilon as an obvious exception)...
The best standard I'd say is "I'll know it when I see it"..
The litmus test would probably be whatever trial code your fraternity has for expulsion of members due to dual membership.
These groups are so different from campus to campus that I don't think any one UNIVERSAL standard can apply to ANY GLO (service, professional or whatever).
We have the right to determine our own membership and each chapter should be able to decide for themselves what double membership entails.
(That's my interpretation on what I've seen on this subject anyhow)
My only question is why would you WANT to be in two socially-aimed college fraternities and do both organizations justice? You're doing both organizations and yourself a disservice by doing it (and your grades might suffer to boot)
LHT
Kevin