Uploading photos in a single view (all portrait or all landscape) will prevent the problem. 

Another option is to turn on smooth height in the carousel style, to do this:
  1. Go to School Website > Website Management > Websites.
  2. Click the three dots next to the site to adjust the style for and select Edit Website. 
  3. Select the Styles tab.
  4. Edit the Style being used on the Photo Carousel.
  5. Select Setup and click Edit Settings.
  6. Select Yes for Smooth Height On.
  7. Click Save & Close.