Double Exposure is a combination of two images to create a single image. you can achieve this cool effect easily by using the actions.
1. Creating Double Exposure for Images using Photoshop.
With the help of this free Photoshop Double Exposure action, you can combine your portrait shots with landscape/cityscape pictures and make the final photo vibrant.
2. Creating Double Exposure for Videos using After Effects or Premiere Pro.
Double Exposures are used in images and also Double Exposures work for Video too.