How to display a 2nd signature based on Check Amount

Hi, we have a requirement to print a second signature on a check when the check amount exceeds a threshold e.g., $25,000. We have created our RTF template with one static image and the second uses url:{xdoxslt:get_variable($_XDOCTX, 'logopath')} to display the signature.

We are using the following statement to test the payment amount

<?if: PaymentAmount/Value >=25000?> <?xdoxslt:set_variable($_XDOCTX, 'logopath', 'FILE_PATH')?> <?end if?>

This works for a single payment but when there are multiple payment in a Payment Process Request once the condition is met all checks after display the second signature even when less than $25,000. I suspect once the variable is set it being picked up for all payments. I tried resetting the variable after the if statement but this did not work.