HI Shruthi,
The root cause of your problem lies in the fact the invalid (expired validity dates) contact persons are getting determined for the account. The reason for this behavior is that your partner determination profile is picking the contact person without considering the validity dates.
Try implementing the BADI which is available for partner determination which can be custom defined to filter the contact persons which are no more valid.
Once this start working, you will not get the invalid contact persons determined and thus the IR will not get created for invalid contact person. An IR always gets created for both contact person and account (depending on partner profile for IR) if you have selected the contact person while confirming the account.
If you don't want to implement the BADI, ensure that you have removed the contact person relationship from the account master by deleting the "has contact person" relation with the invalid contact.
Hope this helps.
Regards,
Divya