It's child's play to forge a test result certificate and given the selfish nature of human beings, I am certain that it's being done. The question is on how to deal with it and create deterrents while trying to be fair to people who might catch it from other people on the way over.

I took a test in HK that was getting me an acceptable certificate. All I had to do was spit in a tube at home so my dog could have done it and drop it at the lab to get the paper the next day in an email. I could make dozens of copies easily changing names and dates in PS.