On adding modules kernel version is not checked

I'm using Ubuntu 13.04 dev with dkms 2.2.0.3-1.1ubuntu2. If a module is added but it already exists with the same name and version but another kernel version dkms doesn't add the module. Here is an example output:

root@ubuntu:~# dkms status
nvidia-current-updates, 304.64, 3.7.0-7-generic, x86_64: installed
virtualbox, 4.1.22, 3.7.0-7-generic, x86_64: installed
virtualbox, 4.1.22, 3.8.0-0-generic, x86_64: installed
root@ubuntu:~# dkms add -k 3.8.0-0-generic -m nvidia-current-updates -v 304.64
Error! DKMS tree already contains: nvidia-current-updates-304.64
You cannot add the same module/version combo more than once.