When in doubt, read the directions:

https://www.irs.gov/pub/irs-prior/i8889--2020.pdf

From page 3, bottom half of center column:

How To Complete Part I
Complete lines 1 through 13 as
instructed on the form. However, if you,
and your spouse if filing jointly, are both
eligible individuals and either of you has
an HDHP with family coverage, you
both are treated as having only the
family coverage plan. Disregard any
plans with self-only coverage.

Also, you should be familiar with the rules for line 6, starting on page 4.

Divide the refigured
contribution limit from Step 1 equally
between you and your spouse, unless
you both agree on a different allocation
(such as allocating nothing to one
spouse).

Translation: Both spouses share one $7,100 limit.  If one or both spouses are over 50 55+, they each get their own additional contribution limit amount added after "agreeing on" splitting the $7,100 (assuming 12 months or December 1st coverage).  If the total contributions to both HSAs exceed the age-adjusted limits then you have an excess contribution problem.

Rick

Edit: To correct age limit.