I think this is what you mean.
a = [1, 1, 2, 2, 3, 3, 4, 4, 5, 5]
b = [1, 2, 3, 4, 5]
for x in a:
for y in b:
if a[x] == b[y]:
#Do stuff here
print "found a match " + str(a[x])
elif y == len(b) - 1:
break
0
solved Comparing values of a list in python with a for loop