All payment (including coupons) will be returned once the task has been cancelled.
This means that a coupon will only be reloaded and able to be used again after the cancellation request has been processed. If the request is still pending, the coupon can't be used on another task.
For more information on the cancellation process, see here.
The terms of your coupon will dictate whether the coupon is reusable. If you're unsure of the terms of your coupon, please feel free to contact us and we can assist.