Hi there!
Thanks for reaching out to us.
The background image depends on the size of the block that contains it. There are no options in the aspect of responsiveness for the background image. You can only regulate this with the size of the block or replacing the background image at the breakpoints.
Duplicating the row is the only interface solution that is in SPPB at the moment.
However, the best option is the use of CSS to replace the background image of the section at the breakpoints, instead of creating the section's duplicate containing another background image.
The following doc may help you:
https://www.w3schools.com/css/css_rwd_images.asp
Best Regards