Only the arcade card pro will work with a converter. A duo arcade card will not.
They both work (usually) with converters. All cards work with converters.
The AC Duo won't work on a TG-16 though, converter, mod, or otherwise, since it has no System 3.0 ROM. Only the Pro will work on a TG-16.
Basically the Duo was a cheaper version for people who already had systems with the 3.0 built in. The Pro will work on any system (converter or mod needed for US systems) since the 3.0 system on the AC will just override the one built in.