Duotone

Duotone is the halftone reproduction of an image using one contrasting colour halftone over the top of another contrasting colour halftone. This is most commonly used to bring out mid-tones and highlights in an image. The most common colours are blues, yellows, browns and reds. 

Here are some examples: 

Here is how I made my duotone: 

First of all I went to Image>Adjustments>Black&White

Then i used the sliders to create my black and white image.

Then i went to Image>Mode>Greyscale

After choosing that I clicked flatten.

Then chose discard.

Then i went to image>mode>duotone

I chose duotone from the drop down menu

I then chose the colours i wanted to use 

This was my final image