Can we use EED with 2 keys $(k_1, k_1, k_3)$ rather than EDE $(k_1, k_2, k_1)$? We measure the strength of DES by the effort (in terms of the number of tries) in finding some $k_1$ & $k_2$ to match a known plaintext and ciphertext pair. Will EED have the same strength as EDE? Which one is stronger?