The first head certainly looks like it did go between cylinders.
The second head is interesting. One combustion chamber looks very oily. The low compression looks like it was poor ring seal or did you do a "wet" compression test on it?
Looking at it I reckon you'll find that head will be as falt as a pancake

Do check valve clearances and valve seating on the suspect cylinder just in case the low compression had an origin in the valves.
Whilst the head is off, I'd be very tempted to replace the valve stem oil seals and at the same time give all the valves a gentle lap.