I've been to both and i must say that i enjoyed park fare more. I thought the food was better but also just teh atmosphere of the grand floridian.
that being said- if u have a character preference- that is obviuosly a deciding factor.
Also, if u have a time preference, look at that also.
And just so u know- LOTS of people on these boards will be less than nice in that you r holding 2 ressies for the same morning.
Definiltey make a decision and cancel one soon- though there is alos the possibility BOTH have been cancelled for you if a CM noticed due to your double booking. Probably not- but cancel one soon to be safe you don't lose both.
Both are great choices!