Hey Mark,
So sorry for the trouble here with recurring events! This is actually something we discovered last Friday and we quickly released a patch for it in Events Calendar 4.2.2.1. I see you are currently running 4.2.2, so I’d definitely encourage you to update.
And, when you do, please read over our release notes. We included a mini plugin that will help clean up all those duplicated events along with instructions on how to use it.
Please give that a shot and let me know if the issues continues from there. 🙂
Thanks so much!
Geoff