What technique did Frances likely use to provide two copies of a portrait photograph for his client?

The technique of setting up two cameras side by side allows a photographer to capture two identical images simultaneously. This method can be particularly useful for providing clients with multiple copies of a portrait photograph without the need for additional processes after the initial shot. By using two cameras, Frances could ensure that both images are taken at the same moment, maintaining consistency in lighting, angle, and subject expression, which is essential for portraits.

Digital duplication refers to the process of creating copies via software or digital technology after the initial photo has been taken, but it may not involve the same level of immediacy and control over the qualities of the photograph as capturing two images at once would. Using a photocopy machine typically pertains to reproducing an existing image on paper, thus not suited for high-quality portrait reproductions directly from the original photograph. Employing a printing press is generally associated with mass production and would not be the ideal choice for producing individual portraits.