Created Unassigned: Updating package (reinstall?) creates packages.config [3685]

I just updated NuGet extension to 2.7. I believe what I then did was either
Update-Package -reinstall xunit
or
used the Package Manager UI to update xunit to the latest version.

This my packages.config before I did whatever I did:

<?xml version="1.0" encoding="utf-8"?>
<packages>
<package id="xunit" version="1.9.1" targetFramework="net45" />
<package id="xunit.extensions" version="1.9.1" targetFramework="net45" />
</packages>

This is my packages.config after:

<?xml version="1.0" encoding="utf-8"?>
<packages>
<package id="xunit" version="1.9.1" targetFramework="net45" />
<package id="xunit" version="1.9.2" targetFramework="net45" />
<package id="xunit.extensions" version="1.9.2" targetFramework="net45" />
</packages>

The puzzle is how did I end up with two xunits?