Real World Adobe Creative Suite 2

These images show why a proper duotone, created in Photoshop, is much preferred over the fake duotone that is created in InDesign.

The original grayscale image is shown on the top left. The proper duotone next to it was created in Photoshop using the curves shown next to each channel. Notice that the midtones for the magenta channel have been boosted and the midtones for the black channel have been supressed.

The fake duotone (below), created in InDesign, lacks the richness of the proper duotone. Its magenta plate is a direct translation of the grayscale image into magenta. The black plate is a direct translation of the grayscale image. The black swatch was then tinted to 15%. There is no subtlety to this fake.