It is per return not per person ... see the form 8888 instructions : Part II You may request up to three different savings bond registrations. However, each registration must be a multiple of $50, and the total of lines 4, 5a, and 6a can’t be more than $5,000 (or your refund amount, whichever is smaller).
https://www.irs.gov/forms-pubs/about-form-8888
