duplicate background layers

Hi,
for an unknown reason, I have duplicate background pages on my website file.
The classic ones, Page Background and Pasteboard Background
Now, there are two copies on top of them "Page Background (2)" and "Pasteboard Background (2)"

Attachment 92940

How can I get rid off them without suppressing everything. They seem to be linked but I don't know how to unlink them.
If I open the "Page Background (2)" layer and suppress all included elements, they disappear, but when I suppress the last one, it entirely suppresses the original "Page Background" itself.
Same for Pasteboard Background.
If I delete "Page Background (2)" it suppresses the original Page Background as well.

Am I missing something? For now I just hide the two copies, but this is not something I want to keep...

Thanks for any help.

Are they on all pages or just one page?

If you Copy the Page and then open a new page and Paste Page, do the duplicate layers come as well to the new pasted page?

It's on all pages, just like the real background layers.

If I copy a page, then click "New page", I get an Error: Internal program error 6408.k.sp.ad
So I can't say whether I can paste everything.
Then I have to quit the application.
If I ask it to keep the clipboard content, launche Xara back, create an empty document and try
to paste the clipboard content, it crashes again with the same error.

WebDesigner MX Premium 8.1.3.23942 DL Sep 14 2012

OK.

Can you manually delete the duplicate layers?

If I manually suppress one of those two layers, the original one also disappear.
Same if I manually delete their elements one by one.
If I deploy the layer "(2)" and suppress its elements, it's fine. When I delete the last one, the layer disappears along with the same name layer without the "(2)". This no matter in which order I suppress the elements.

I installed Webdesigner in a VM to see whether the PC has a problem, but it behaves the same way, with the same errors.
Also launched it and opened my document, made sure to have an empty clipboard, duplicated one of the pages and it crashes immediately.
I don't know where those duplicate layers come from actually...

Also, once it crashes, then I have a second error message: Spurious internal error has occured.

Steve