Photograph manipulations have been existing ever since the camera was invented in the 19th Century. Back then, they used laborious techniques such as cutting and pasting of pieces of photographs, retouching with ink, re-photographing the composite image, etc. The manipulation was often used for more serious purposes than the simple retouching by all portrait studios as an accepted practice. For example, the original photo of Stalin and Commissar Nikolai Yezhov was censored after Yezhov was executed in 1940s.
In old communist China, the photos of Mao Tze-Tung and other leaders were often altered, especially when the leaders were purged.
In the 21st Century, photos are sometimes manipulated in the recent purge of North Korea and in the western press. The western photographers occasionally alter their photographs to enhance the original images and the saleability of the photographs, although the journalist community has now set up a code of ethics on photograph manipulation.
With the advent of digital technology, the photographs can be easily enhanced and altered before they are downloaded from the camera or after they are downloaded and modified by software.
For fun, I had experimented with compositing photographs several years ago. One of my own picture at a tourist yacht and a photo of British naval commandos were used. Some minor alterations to my picture by cropping out unwanted parts and enhanced the man on my left using a simple Photoimpression software. Then the commados image was mounted and sized down onto my picture with edge blending using a composite software.