It was reported in #2623 that updating plugin, without dismissing notification from previous update, leads to doubling up notifications.
It would make sense to clear previous notifications and only retain the most current one on update.
I've seen this happen.
It would also be great if the update notification didn't get shown for every point release as well.
This was fixed in 2.3. When upgrading from Yoast SEO >= 2.3 to a higher version, the duplication will no longer occur.