When updating the credit card payment information on a recurring gift all gift with the same card are updated, not just gifts for the same constituent
CRM ties the credit card information to the commitment not to the constituent, so if one commitment using that credit card number is updated all will be updated.
Steps to Duplicate
1. Create a recurring gift for a constituent and enter credit card details. 2. Create a recurring gift for a different constituent and enter the same credit card details. 3. Open one of the recurring gifts and click the edit button next to the payment method 4. Enter a different credit card than what was previously used. 5. Click the Yes button on the popup that reads, "Other commitments use the original credit card. Would you like to update them to use the new credit card?"