The Feds rejected my Turbotax efile because of "duplicate 1099-Rs." However, one is for me and one is for my husband. How can I differentiate?

First, be sure you have assigned each to the proper person.  Increase the amount on one of them by $1, and decrease the other one by $1.

When you start to enter a 1099-R, on the screen that asks what kind of 1099-R you have, there is a line near the bottom that says "This Form 1099-R belongs to" and shows both of your names. Select the appropriate name for each 1099-R that you enter. See the screen shot below.