I used the SortInfo program to make a little web page to help find out stuff like this. You can check it out at
http://jstookey.com/arcade/sortinfo/index.php . The searches that I did below do not include clones. Also, this list is generated from the Mame's listinfo, which is not always correct or accurate, so this list might be missing some games, and misrepresenting some others. In general, though, it's a VERY good place to start when getting a list together.
Here's a list of Dual 8way games:
--------------------------------------
http://jstookey.com/arcade/sortinfo/index.php?num_switches=1&do_search=1&switch0=control&operator0=%3D&switchvalue0=doublejoy8wayAngel Kids (Japan) (angelkds)
Apocaljpse Now (aponow)
Bandido (bandido)
Black Widow (bwidow)
Cloak & Dagger (French) (cloakfr)
Complex X (complexx)
Crazy Climber (Japan) (cclimbrj)
Crazy Climber 2 (Japan) (cclimbr2)
Dribbling (dribling)
Front Line (frontlin)
Indoor Soccer (idsoccer)
Inferno (inferno)
Joyful Road (Japan) (joyfulr)
Krull (krull)
Libble Rabble (liblrabl)
Lost Tomb (easy) (losttomb)
Mars (mars)
Minefield (minefld)
Rescue Raider (rescraid)
Robotron (Solid Blue label) (robotron)
Rock Climber (rockclim)
Screw Loose (prototype) (screwloo)
Smash T.V. (rev 4.00) (smashtv4)
Space Dungeon (sdungeon)
Space Position (Japan) (spcpostn)
Splat! (splat)
Star Guards (stargrds)
Stompin' (stompin)
The Return of Ishtar (roishtar)
The Tin Star (tinstar)
Total Carnage (prototype, rev 1.0 01/25/92) (totcarnp)
Ultra Tank (ultratnk)
Water Match (wmatch)
Wild Western (set 1) (wwestern)
And some dual 4 way games:
----------------------------------
http://jstookey.com/arcade/sortinfo/index.php?num_switches=1&do_search=1&switch0=control&operator0=%3D&switchvalue0=doublejoy4wayFire Trap (Japan bootleg) (firetpbl)
Karate Champ (US VS version) (kchampvs)