Deleting other templets meta box values

So while I was away working on other projects my content team used a Duplicate post plugin to create new pages instead of add new page... and now every page has a custome field box at the bottom with the metabox data from each of the previous pages.
ie

1. make a new page
2. input the info
3. hit save
4. duplicate the page change the template(hid show kicks in and shows the new set of metaboxs)
5. input more data
6. hit save
7. duplicate that page
8. and so on
9. and so on

So now the dashboard is loading slow and before I pluck the custome fields out of the DB by hand or wirte a script that does to do it...is there a way to do a one time flush/deletion of the unused metaboxes for each page?