I have been taught several things differently by different instructors. The best solution is for the student to perform the material the way the instructor standing in front of him tells him to perform it, and then analyze the situation later, with the same instructor, a different instructor, or on his own, and look for similarities and differences and see what can be learned from the experience.
I have seen this very situation give rise to all sorts of foolishness on the part of students and instructors alike. The instructor will sometimes get uppity and superior and tell the student "this is how it is and this is how its going to be," that accomplishes nothing positive. At the same time, I know students who simply refused to do as an instructor asked during a group class because, "that's not how Mr. X taught me to do it, so I just ignored the instructor." This is also silly because the instructor was put in his position for a reason, to ignore what he's trying to share with you because it's new or different is small minded and foolish, not to mention that it undermines his position and disrupts class, possible hindering other students from learning the lesson the instructor is trying to teach.
As an instructor, I tell my students, perform the material this way, if an instructor asks you to do it differently, before you tell him no find out why he thinks its a good idea. Then play with both ways later on. Worst case scenario, you'll find out which one works better for you, and learn a little more about why to do or not do certain things. Best case scenario, you learn two different ways to accomplish the same goal.
Instructors have to be willing to admit they don't have the monopoly on what is right and wrong, and they need to teach their students to be open to many different ideas and how to find the lessons contained within each. Students need to be willing to learn, really learn, and not just to parrot what Mr. X taught them.
-Rob