Missing warning message for overriding a review with a delegate approver

Reproduction steps:

• Enable delegate approvers mechanism and provide 2 delegates
• With first delegate perform a review on a CR
• With second delegate, perform a review on the same CR

Expected result:

• Second delegate should see a warning that a review already exists that will be invalidated

Obtained result:

• the warning is only displayed if the same delegate perform the review twice, no warning is displayed for the second approver