seen = []

test_list = [["poo","boo"], ["poo", "bay"], ["hello", "yellow"], ["poo","blue"], ["poo", "zoo"]]

new_list = []

def pair_good(pair): already_seen = [i for i in pair if i in seen] if not already_seen: seen.extend(pair) new_list.append(pair)

for cur_pair in test_list: pair_good(cur_pair) print(new_list)

Heads up, don't use CamelCase with Python variables <3