It is not possible to upload and Display more than one logo at a time on your video pages in the designated Logo place.
However, the video below provides a workaround to represent more than one brand/ display more than one logo at a time:
1. Use a free tool like Google Slides, Canva or other to create a 1280x720 background image (the typical dimensions of a powerpoint/google slides slide)
Place your Logo in the top part of the background like the example below, then save the background image as a JPG or PNG
2. Upload the custom background to your video page or Preset
3 View logo on video page as a background, instead of the typical logo place