Hi, I just updated to WordPress 5. I am still in the process of setting up my first event. I checked the preview of the thank you page and it has the same message 3 times, two at the top of the page and one in the content area. I checked the page editor and couldn’t see anything unusual (except for Gutenberg!). Here is a screenshot:
I don’t know if the page will display this way live or if it is a preview glitch.
The Thank you page does not support previews because it’s used by Event Espresso to show information after a transaction.
If you want to get a preview of the Thank You page, you’ll need to set up an event (you can save the event as a draft if you don’t want to publish it yet). Then you’ll view the preview of the event, then you register for the event. If the Invoice option is still activated, you can finalize the registration at checkout by selecting to pay by Invoice. Then you can view an example of the Thank You page.