2012.1 python-glance installation error

Hello all,
When I install python-glance, there is a error occurred. Please help me out. Thanks.

dpkg: error processing /var/cache/apt/archives/python-glance_2012.1+stable~20120608-5462295-0ubuntu2.2_all.deb (--unpack):
 trying to overwrite '/usr/share/pyshared/glance/api/cached_images.py', which is also in package glance 2011.3
No apport report written because MaxReports is reached already
                                                              dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)
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Processing triggers for python-support ...
Errors were encountered while processing:
 /var/cache/apt/archives/python-glance_2012.1+stable~20120608-5462295-0ubuntu2.2_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)