EZNEC azimuth plots for a 20m half-wave dipole (black) vs. an 88' doublet, with both up 40 feet and in flattop configuration. The 88' doublet has 2.55 dB additional gain vs. the half-wave dipole (or vs. an EFHW). Out here on the west coast, we would try to erect the antenna with the broadside lobe pointing at 80/260 degrees for best coverage of the central and eastern U.S. on the SOTA Money Band (20m).
Note that this gain advantage only occurs when the antennas are in flattop configuration. As you bring the ends down more and more, the doublet loses more and more of its advantage over the half-wave dipole or EFHW, but is never worse than either antena.