Abreast-DM
Two Davies–Meyer steps side by side under the same key, one of them fed the bitwise complement of the chaining value so the two do not collapse into one.
This is the parallel half of Lai and Massey's 1992 proposal. Both halves are encrypted under a key made from the message block and the other half of the chaining value, but one encryption gets its plaintext complemented. Without that inversion the two steps would compute exactly the same thing and the doubling would be purely decorative.
Unlike Tandem-DM, the two encryptions can run at once, though the key schedule still has to run twice. Its collision resistance was proven in the ideal cipher model around 2009–2010, nearly two decades after publication — a common fate for constructions that were sensible long before the theory caught up.