Update to Version 4.8.3 kills local Database

I tried to update my Oxid Version 4.7.8 to 4.8.3. But it ended in a desaster.

Now i can't go into my localhost, because of database errors.

I guess it was my fault, because i have overwritten the files in "copy_this" instead of copy this folder to my oxid installation.

So I thought, that it is time go back and i reloaded my old files and the database.

But this is not possible, because it says, that there are duplicate entrys (for primary).

So what did i do wrong?