Actually you need Audyssey SubEQ in order to do dual subs. IIRC you can have Audyssey XT32 without SubEQ but not SubEQ without XT32, which means both of your choices won't do dual subs as well as a receiver with SubEQ. That may have changed, but I somewhat doubt a company would pay extra for SubEQ to be added without XT32.
Otherwise if you try to EQ your subs with EQ or XT it'll try to do them both as one sub. The results won't be terrible, but they won't be as good compared to if they were done individually.