According to producer Dae Bennett, Neumann U47s were used to record Bennett and his guests on Duets II.
"My vocal setup for the recordings with the quartet consisted of two Audio-Technica AT4047 mics, going into a Neve 1073 and then a [Urei] 1176. I normally like to use the classic Neumann U47 for recording vocals, but they would have picked up too much of the room. The AT4047s have a tighter cardioid pattern and also sound very good. In the sessions when the vocalists sang to the locked two-track edits, I did use two Neumann U47 mics."
(...) "We set Tony and Amy [Winehouse] up with playback speakers and two [Neumann] U47 mics, and what you see in the video are the actual vocal takes that I selected for my edit. The signal chains were the same: Neve 1073 and then an 1176 and then going into Pro Tools. I recall that they did about five or six takes. You can see some mutes in the vocal takes, which is where there may have been too much leakage or too much of the sound of the room. But in general I left the spill. The string arrangement was added later."