Python - compare list elements and return the value -

how check elements in list
example:

>>> l [1, 2, 3, 4, 1, 2] 

i want compare l[0] & l[1] elements , return me 1 , 2 if match other elements in list.

if l.count(l[0]) > 1 , l.count(l[1]) > 1:     print l[0], l[1] elif l.count(l[0]):     print l[0] elif l.count(l[1]):     print l[1] 

or list comprehension

[i in l[:2] if l.count(i) > 1]