So i've got this problem that i'm facing, whenever I'm provisioning my sites some content editor webparts become duplicated while others don't. There isn't any difference between them except... I'm running publishing with a custom pagelayout with 3 zones. Every zone is populated but only one webpart becomes several instances of
?contents=1" at the end of the URL of the page, it will open Web Part Page Maintenance page. check whether there are duplicate web parts on the page.
I suppose that there are scripts in the Content Editor web part. When you view the page, the content displayed in this web part gets duplicate.
Instead of just copying and pasting scripts into the Content Editor web part, you should enter the code to a file, store the file in a SharePoint library and then link this file to the Content Editor web part.
Refer to the following blog for more information. This blog has good information though it is for SP 2010.
Provide some screenshots for checking your issue if the issue still exists.