The duotone effect: what it is and how to create a duotone design - 99designs
What Is the Duotone Effect? (+How to Use It in Your Designs)
Free PSD | Duo tone effect to your photos
121 Duotone Lightroom Profiles, Add-ons - Envato Elements
Bottom view of the famous Statue of Liberty, icon of freedom and of the United States. Light blue and yellow duo tone effect applied Stock Photo - Alamy