Manage content page duplicated

I have a strange issue with a site where the manage content page has suddenly duplicated every single page (other than the homepage) and region so that it has doubled up. There are now two of each page and two of each region. The new pages and regions have no content in them and as such it has made the site see none of the entered content. I have seen this happen once before on a site but as it was small I just deleted the doubled up pages and it was fine. This site is much larger and so it is more of a problem as deleting the duplicated region and page and then refreshing the site causes it to just create another duplicated version. Its as if its stopped seeing the original content altogether. Any idea at all what could have cause it? The only thing I have done recently is updated a page with a new perch_content_custom and added an image file outside of the cms. Otherwise it has not been touched at all.