install error

aamir@aamir-pc:~$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  extlinux syslinux-themes-debian-squeeze syslinux-themes-debian
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
  libnm-glib2
The following NEW packages will be installed:
  libnm-glib2
0 upgraded, 1 newly installed, 0 to remove and 28 not upgraded.
Need to get 0 B/64.2 kB of archives.
After this operation, 274 kB of additional disk space will be used.
Do you want to continue [Y/n]? y
(Reading database ... 182575 files and directories currently installed.)
Unpacking libnm-glib2 (from .../libnm-glib2_0.8-0ubuntu3.3_i386.deb) ...
dpkg: error processing /var/cache/apt/archives/libnm-glib2_0.8-0ubuntu3.3_i386.deb (--unpack):
 trying to overwrite '/usr/lib/libnm-glib-vpn.so.1', which is also in package libnm-glib-vpn1 0.9.1.90-0ubuntu3
Errors were encountered while processing:
 /var/cache/apt/archives/libnm-glib2_0.8-0ubuntu3.3_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)