iCloud calendar sync issues

Hello, A few days ago I noticed that my Mac was not able to send mail when I traveled, yet I could save it as a draft and then send mail from my iPhone. I checked the outgoing mail server settings and they were the same on Mac and iPhone. Thinking there was an iCloud issue, I logged out of iCloud on my Mac, then signed back in. Now my calendars are all messed up! I have five different calendars and now they all have multiple duplicates after signing out, then back in. I'm looking for advice on what to do to delete the unnecessary duplicates. Any suggestions, wise ones?