Finally, here are some details on the 2-player levels. There are 16 compared to Amiga's 20. Most are just verbatim copies of the Amiga levels though. That said, there is one 2-player level in arcade version (#4), "Battle at Midway", that is not found in Amiga version. [edit: added more information about that level] It was the level from the Amiga Lemmings demo that was dropped from the final version of Amiga Lemmings. I've attached a picture of the level based on the rip of the level from Amiga demo; I've confirmed the arcade and Amiga demo versions of level are identical. (The blue/green rectangles around the entrances are obviously just drawn by me to help indicate which entrance is for which player.)
You can refer to jaycee900's
book, specifically
these pages, to see what the Amiga 2-player levels look like.
(Skillset given as [climber floater bomber blocker builder basher miner digger]; "-" means none of that skill)
1. Still everything to play for [20 20 5 10 50 50 40 40] (Amiga #2)
2. In the thick of the fray [10 10 20 20 80 20 20 20] (Amiga #3)
3. Game on! Choose your tactics. [10 5 5 10 30 20 20 20] (Amiga #4)
4. Battle at Midway [1 1 5 5 40 1 1 1] (Amiga demo #2)
5. Good game! Good game! [5 5 15 5 40 10 10 10] (Amiga #5)
6. The Rubbish Dump [50 each] (Amiga #6)
7. and the winner is..... [20 10 10 10 50 20 20 20] (Amiga #7)
8. Any chance of a truce? [10 - 5 10 40 20 20 20] (Amiga #8)
9. The Pipe Room... [10 10 10 10 10 20 10 10] (Amiga #9)
10. The Rope Bridge [10 - 20 - 50 10 5 10] (Amiga #10 modified)
(modification: entrances moved to center of "rope bridge", both at same position [so both sides come out at exact same spot])
11. There can be only one [5 5 15 5 20 5 5 5] (Amiga #1)
12. Just for fun or to the death? [10 10 5 - 40 10 10 10] (Amiga #11)
13. The Crystal Cavern Mark II [10 - 5 10 20 10 10 10] (Amiga #12)
14. Cross-over Point [10 10 10 - 40 40 - 40] (Amiga #13)
15. The Passing Place [2 1 - - 50 20 20 20] (Amiga #14 modified)
(modification: center column of steel is inverted compared to Amiga, so in arcade it's 4 steel blocks at the top, then the gap, then 2 steel blocks at the bottom)
16. Take what you can, when you ca [- - 20 10 50 20 20 20] (Amiga #15 modified)
(modification: "cones" [like the ones featured at the bottom of
this level] added near the ends on both sides of bottom platform)
The title for #16 is not a typo, it really is cut off before the "n" in the game. I guess the arcade version doesn't have enough room to fit very long titles.
#6 is affected by the glitch where lemmings can walk up and across ceiling off the level area's top boundary (in DOS/Amiga versions, lemmings turn around if they get too close to top boundary). At the entrance "pit" area, this allows lemmings to walk off on the right side out of the pit, but not the left side (because the terrain is asymmetric, and there is too high a step on the left to walk past).
#13 has an unexpected trap placed to the right of the green (right) exit. No such corresponding trap is seen for the blue (left) exit. Not sure if the Amiga version's trap-free, has same one-sided trap, or has traps for both exits.
Finally, the fast-forward/pause function still works in 2-player mode! In fact each player has their own button to cycle through fast-forward/pause/normal that only affects their lemmings. Not sure whether they really intended for this.