Cannot checkout a branch / worktree shows multiple branches for the same directory

Hi,

I stumbled upon an interesting problem when checking out a branch. I had to switch to a testing branch to merge in some changes from yet another branch, but when I tried to check out the testing branch I got a message saying that I'm already on the target branch.

I used worktree a few times, but the checkouts were always in their own directories. It crossed my mind that this behaviour may be related, so I took a look at the worktree list and noticed that according to that list there are three branches at the same time in one directory.

It may be a conicidence and I have no confidence in saying that these issues are related. Can someone shed some light on this issue for me?

    $ git --version
    git version 2.7.0.235.g07c314d

    $ git status -uno -sb
    ## ticket-22444
    M src/core/parsers/ParserBase.py
    M src/core/parsers/test/ParserBase_test.py

    $ git stash
    Saved working directory and index state WIP on ticket-22444:
7c5edaa #22444 refactoring
    HEAD is now at 7c5edaa #22444 refactoring

    $ git co testing
    fatal: 'testing' is already checked out at '/home/k/workspace/moyo'

    $ pwd
    /home/k/workspace/moyo

    $ git branch | grep '*'
    * ticket-22444

    $ git worktree list
    /home/k/workspace/moyo  7c5edaa [ticket-22444]
    /var/home/k/moyo-lsf  349613d (detached HEAD)
    /home/k/workspace/moyo  265b7f9 (detached HEAD)
    /home/k/workspace/moyo  c852282 [testing]

    $ uname -a
    Linux k 3.13.0-83-generic #127-Ubuntu SMP Fri Mar 11 00:25:37 UTC
2016 x86_64 x86_64 x86_64 GNU/Linux

    $ cat /etc/lsb-release
    DISTRIB_ID=Ubuntu
    DISTRIB_RELEASE=14.04
    DISTRIB_CODENAME=trusty
    DISTRIB_DESCRIPTION="Ubuntu 14.04.4 LTS"

Thanks, Krzysztof