how to check if two numbers in a list are the same in Python

I have a little problem with some coding. This is my code:

def sites(x):
    r = []
    sum = 0
    i = 0
    modulo = []
    som = 0
    j = 0
    while i < len(x):
        sum = int(float(x[i])) + (i + 1)
        r.append(sum)
        i = i + 1
    while j < len(x):
        som = r[j] % len(x)
        modulo.append(som)
        j = j + 1
    return modulo

If I for example fill in sites("321") this code will give me the list [1, 1, 1]. What I want to do is check if there are numbers in this list that are the same. I was thinking about something like:

if modulo[0] != modulo[1] != modulo[2]:
    print "valid"
else:
    print "invalid"

This only works when the input in sites is three digits long. I've been brainstorming on how to use a while loop that checks every digit.

All help is very welcome.