title: Concatenate images from folders by their ORDER in python
body: <p>I know how to concatenate two exact images, but I need to combine two images each from their own folder. I cannot do it by name of the image or don´t know how to do it with a list of pairs. <strong>Is it possible to concatenate all images (always two, one from each folder) by the order of images?</strong> They are sorted by time of download so they match in order, not in exact time of download.
  Thanks.</p>