Generating unique, ordered Pythagorean triplets

This is a program I wrote to calculate Pythagorean triplets. When I run the program it prints each set of triplets twice because of the if statement. Is there any way I can tell the program to only print a new set of triplets once? Thanks.

import math

def main():
    for x in range (1, 1000):
        for y in range (1, 1000):
            for z in range(1, 1000):
                if x*x == y*y + z*z:
                    print y, z, x
                    print '-'*50

if __name__ == '__main__':
    main()