Couple MFJ owns 2 homes and live in both at different times of the year. The rule of 2 out of last 5 years applies to both homes. 

In 2020 sell 1 home, capital gain of 300K. Not entered on taxes as gain is exempt and no 1099-S was generated.

In 2021 they sell the 2 nd home, capital gain of $150k, no 1099-S.

Can I exclude the 2nd home sale in 2021 taxes as together the total gains are less than $500k, and no other sales have occurred in the past 5 years? Or does the first gain of $300k in 2020 where exemption was taken exclude them from taking a 2nd tax-free gain in 2021?

Thanks for any advise

Nolan