You are definitely having an issue with duplicate field keys, i have see this happen when duplicating a field in one layout and then moving it into a different layout, but I have never found the cause. If you don’t have data saved in these fields yet then you’re best bet is to delete all of the fields with duplicated keys and recreate them. Another choice would be to edit the json file and make sure that all the keys are unique, you could simply tack on a 1, 2, 3 ect to each key, then update the date modified value in the json file and sync the field group. These are the things I’ve done in the past when I’ve had the issue but then I was in the middle of building and it was not on a site with live data to worry about yet.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
Helping others is a great way to earn karma, gain badges and help ACF development!