Retarget to WindowsPhone 8.1 - The payload contains two or more files with the same target path

Question

My solution builds without problems / errors until I updated my WindowsPhone 8.0 project using the "Retarget to WindowsPhone 8.1" option.

I get the following error:

The payload contains two or more files with the same destination path 'Newtonsoft.Json.xml. Source files: C: [mypath] \ Bin \ Debug \ Newtonsoft.Json.xml C: [mypath] \ packages \ Newtonsoft.Json.6.0.8 \ Lib \ portable net40 + sl5 + wp80 + Win8 + wpa81 \ Newtonsoft.Json .xml

I tried to follow without success:

• Remove all Json links using nuget and manually and reinstall it.
• Clear solution, rebuild solution, restart VisualStudio
• Delete bin and obj folders and restore solution

The only thing that helped was to set the "local copy" for the Json link to false. But this is not a clean solution in my case ...

Can someone explain to me what is going wrong?

Edit

Another solution to this problem is to delete the XML files in the "packages" folder or rename them. But this is also not a clean solution ...