Content-Elements issue after duplicate

I tryed to duplicate an content-element. After that i tryed to move it to another position in my layout. I wasn’t able to move the content-element. I also tryed to create a new one. Same issue here. It looks like its floating above the layout and is freezed. I cant move, delete or edit the content-element anymore.
Console gives me the hint that there are multiple DOM-Elements with non-unique IDs, might this be relevant to the issue? Also got a Uncaught Type Error Can not read property match of undefined.

Any solutions? Site was updated by customer before. Is it possible to do a version rollback?

Thanks for your sugestions!