The Client Certificates preference page determines what client certificates will be presented to the server during recording and playback.
The Recording section 
determines which certificate
will be presented during the recording process. The certificate(s) must
be imported using the Import
button. Certificates are protected by a password, use the Test
Password button to test the password entered for the selected certificate.
The Replay section 
determines which certificate will
be presented by each virtual user during the replay of a testcase.
To configure each virtual user to use a different certificate, they must all be imported into Analyzer. In addition, a dataset must be created containing two fields:
After creating the dataset, configure the Dataset, Client Certificate and Password fields. Use the Test Passwords button to validate the configuration. Depending on the number of certificates, testing the passwords could take several minutes.