combinations - dealing with duplicates in combinations

from itertools import combinations 
import numpy as np  
def dcomb(l, r): 
  
    # returns a list of all subsets of ur list 'l',  of length r 
    
    return set(list(combinations(l, r)))
    print(combinations(l, r))
    
l = [1,2,2,4] #2 is duplicated
r = 2
dcomb(l, r)


#print("total number of combinations =",len(dcomb(l, r)))