As of about two weeks ago, you should not be receiving any expiration emails for certificates which you have already renewed starting from that date.
Before that, Let's Encrypt didn't actually check whether there was a more recent certificate that's not close to expiring before sending an email.
tl;dr: You might get some additional notifications for certificates issued more than ~2 weeks ago, but for any future certificates, things should be accurate.
This post has some more details: