Generally I would agree that it is a good idea to have paper certificates attached to your reservation. However, sampler rewards are a little different. If you have them attached all the unused portions of the certificate will be attached to a single reservation. The reason they were issued as paper certificates was because systematical it was nearly impossible to attach the separate portions to different reservations. If you are using all the portions for single location attaching the certificate is not a bad way to go; however, if you are going to be staying at multiple locations with you hopper reward you may run into some problems.
If you are using the hopper the best way to stop the auto order process is to make sure the reservations agent knows you are using the hopper reward. They are able to flag the reservation so no award is auto issued. If you have any concerns that your reservation has not been set up to stop the auto order process send me a personal message with your confirmation numbers and we will be glad to check them for you.
Ira