How to ensure that the acceptance letter received is real and not a mistake? Recently a very popular name-brand university has been in the news for the wrong reasons. 

I quote from a national newspaper's article that it has "accidentally admitted 800 candidates ... only to retract the offer about seven hours later". 

As a prospective applicant who has received offers from two non-"name brand", dream schools, I shudder at this fact. I am forced to anticipate disappointment when I should actually be relieved after the typical stressful and anxious wait.

As an international student, I seek information on whether many universities do retract their acceptance letters weeks after sending them. What are some ideal ways to ensure that the acceptance letter received is full and/or final?
The best way to know that you are not in a mix-up is to email a real person. As an international student you really need to speak to someone and you can ask for it. I recommend you to set up an skype interview, even before they accept you. I am sure you have tons of questions besides if you are accepted or not, and you should worry more about finding an education that is a good match for you. Still, I wouldn't assume the worst, that mix-up was an isolated case and not the norm.