Short version: The base EU2000i has a duplex receptacle rated at 20A, and power made is 13.3A. If 2 x units are connected in parallel, the total possible current is 26.6A, which exceeds to rating of the receptacle. Also, power shared via parallel ports does not flow through the 20A circuit breaker. These conditions are not allowed by CSA, so no parallel ports on Canadian EU2000i generators. The EU1000i is okay, since its 15A receptacle never flows more than 15A, even with a second EU1000i connected in parallel.
More details
in this thread.-Robert@Honda
Caveat: I work for Honda, but the preceding is my opinion alone.