Help - Duplicate icons in top left corner of screen

Just been using my iPad, and during an app update (a free one from the apps store), my screen suddenly changed, and now the home screen has a pile of icons on top of each other in the top left corner of the screen. These icons are duplicates of the ones on my home screen, and the ones in the original places don't work.

I can drag these new icons away from the top left, and I end up with two of each icon on the home screen, but only one works. Also, I can drop them anywhere on the screen, and other icons don't move to make way like they did before. However, as soon as I scroll across to another screen and then scroll back to the home screen, the pile of icons is back in the top left.

There is also a new icon called Productivity, which looks like a container for other icons. I have no idea where this came from, as I've never seen it before. If I open it, it has three of my apps inside, messages, ibooks and notes. I can drag these back onto the home screen, but again, when I scroll away and back, things are as they were with the three apps inside this productivity.

Anyone any idea what's going on? The iPad is pretty unusable now.

Thanks for any help.