DUOTONE
Often you will find yourself using only two spot colors in a project that has halftone images. Creating a duotone is a fantastic way to elevate the appearance of an image and create a more interesting and richer layout. Duotone is a technique used to give more shadow density by overprinting two halftones using two spot colors.
Simply a DUOTONE is a two color halftone reproduction from a one-color photograph
What is and How to Make a Duotone
Duotones from Photoshop and Duotones in Indesign
