These are not the same certificates - they are two different certificates with the same key-pair.
Owner: CN=TUE 1-TUE 1 ADMIN-187413
Issuer: CN=Test CA, OU=For Test Purposes Only, O=A Ltd, C=IE Serial number: 3d43ebb325f79c6d6ce475f8514fc626 Valid from: Wed May 02 01:00:00 BST 2012 until: Thu May 31 00:59:59 BST 2012
Owner: CN=PUE 1-PUE 1 Admin-294937
Issuer: CN=Test CA, OU=For Test Purposes Only, O=A Ltd, C=IE Serial number: 1bf9f63394d41471538a4bbc25deff3 Valid from: Wed Jun 13 01:00:00 BST 2012 until: Thu Jul 12 00:59:59 BST 2012
This is not uncommon in PKIs. Certificate Policies (CP) vary from company to company and for various business reasons. This CP, obviously, permits re-using the key-pair for renewals of certificates (which is what this is). It is also not uncommon to change the CN during a renewal for a role-based digital certificate (although, they could have done this with another key-pair also - but its hard to surmise without knowing the details of the business process).
Since it is completely normal for an expired certificate to verify a digital signature that was created when the certificate was valid, there is no cryptographic problem in your use-case. The cryptography and technology is doing exactly what was designed and expected of digital certificates.