Git fetch --all - additional branches are created

Question

I have a USB drive configured as a git repository (don't ask why), but I just did git fetch --alland received these messages:

   38ea2b1..2b4fdaf  master     -> usb/master
 * [new branch]      usb/branch/A -> usb/usb/branch/A
 * [new branch]      usb/branch/B -> usb/usb/branch/B
 * [new branch]      usb/master -> usb/usb/master

which looks alarming.

It seems that additional branches are created that are not needed. Will this be the beginning of an endless cycle of branches usb/usb/usb/usb?

What should I do to crush this and avoid the problem?

==== UPDATE 1

In .git/configI have:

[remote "usb"]
        url = /path/to/usb/repo.git
        fetch = +refs/heads/*:refs/remotes/usb/*

which looks pretty standard. But then, right below it, I have such strange things:

[branch "branch/A"]
        remote = usb
        merge = refs/heads/branch/A
[branch "usb/branch/B"]
        remote = .
        merge = refs/heads/branch/A
[branch "usb/branch/C"]
        remote = .
        merge = refs/heads/branch/A

It continues. Only about 20 entries.

What's going on here?

==== UPDATE 2

My USB project.git / config contains:

[remote "origin"]
    url = C:/xampp/htdocs/networkroot/.

Not sure if it should be so.