... technically there are twin-engine aircraft where the propellers can't be feathered. An example:
Slatye,
Ha! I just knew somebody would come up with some ultra obscure twin that had fixed pitch props - and that it would be British!
Well, in this case this type is American. A quick look over that Wikipedia page brought a few laughs - thanks! Here are a few quotes from that page:
The Lancer's performance when flying on a single engine is notably poor; in a column for AOPA Pilot, author Barry Schiff summarized the airplane's single-engine performance by writing that "...it doesn’t have any".
The engine nacelle placement hampers visibility,[3][4][6] particularly for the rear-seat pilot,[4] and for both pilots during banked turns.[3] Schiff compares the engine nacelles to "...horse blinders that [result] in disorienting tunnel vision".[4]
The close proximity of the engines and propellers to the front-seat pilot's head create elevated noise levels described as "remarkable"[3] or even "paralyzing".[6]
Its lackluster performance is generally attributed to abundant form drag from the wing and tailplane struts and unusually large strut-braced fixed main landing gear legs, which are about 3 inches (76 mm) in diameter and 5 feet (1.5 m) long.[2][3][4]