MDR & Palo experiences from 3 weeks ago:
In the MDR, DH and I regularly each ordered an entree and then each asked for the meat/seafood item from another entree "on the side". It was never a problem, we were graciously accommodated.
At PALO, I ordered the stuffed chicken breast entree and asked for a "side" of the scallops. DH ordered the Lobster ravioli and also asked for a side of the scallops. Our waiter, said "Of Course, not a problem". We each received a silver dish holding two beautifully done scallops along with a small serving of the accompaniment.
We have never been questioned about wanting or denied a "side" or full 2nd meal.
If you want an additional meal or side dish, go for it. I would however never order more than I would eat. I would not order 2 meals and only take a bite or two of each one, but that is me. Waste not, want not.