The correct answer is:
Sonic 4 Episode 2: Oil Desert Zone Act 2 [left]
Shadow The Hedgehog: Circus Park [right]
Full results are also here:
juribesite ~ Oil Ocean Act 2
kennysuavo ~ sandopolis act 2 and carnival night
TheZerker45 ~ I....I..I. just don't know :_(
ThePetz13 ~ Sonic 4 Episode 2: Metal Sonic and idk on the right speaker
Franchico60 ~ A bit hard, huh?
heartis TV ~ This one is hard. Hard as a rock.
MRL56789 ~ Left: Sonic the Hedgehog 4: Oil Desert Zone Act 1
Right: ??? Sounds very familiar, but have no idea
MrBucknasty2000 ~ Right- bonus stage sonic advanced
EPshows ~ Agh! The only 1 I have been active for and I can't even name 1!
samuroleon ~ I have no idea
capsule56 ~ That feel when you totally recognize a song but you can't name it.
ThePIKAX360 ~ Left is Sonic 4 ep 2 Oil Dessert Act 1 and Right is Shadow The Hedgehog Circuit Park.
diogopm99 ~ sonic 4 ep 2 oil desert act 1 and circus park from shadow the hedgehog
shayrafa ~ sonic 4 ep 2 oil dessert act 2 and sonic shuffle something im sorry i dont know the one on the right
Wii360XX ~ Hmmmmmm.
Oil Desert act 2 from sonic 4 episode 2....
and........ Mystic cave remix for sonic 2?
shadnic2012 ~ left ear:sonic 4 ep.2 oil desert act 1
right ear:shadow the hedgehog casino park
SilverCoatLion ~ Oil Desert act 2 White Park act 2
2percentmilk555 ~ Left: Sonic 4 Episode 2 Oil Ocean
Right: Carnival Night Zone remix?
BKRagequitz ~Left - Sonic 4 Ep. 2, Idk which stage
Right - Some type of carnival
Iceeman234 ~ Left: Oil Desert Zone act 2
Right: Shadow the Hedgehog Circus Park
NiGHTSRealaJackleFan ~ I heard that one circus park song from shadow the hedgehog... but that's all I can figure out ^^;
stickpeople14 ~ circus area shadow the hedgehog and i dont know
Senecathehedgehog484 ~ Shadow the Hedgehog (Circus Park)
Sadiq Wade ~ The left one is Oil Desert from Sonic 4 Ep II and the other one.....i don't know. :/
lobo14ful ~ left - oil desert act 2 (sonic 4 episode 2)
Ketch1730 ~ left: Oil Ocean Act 3/ Sonic 4 Ep 2
right: Circus Park/ Shadow the Hedgehog
TheROFLcopter66 ~ The one in the left speaker is one of the Oil Desert acts in Sonic 4 Episode 2. I don't know the other one
Dortizr160 ~ the first song is from shadow the hedgehog circus park. i dont know the second :(
SkateLabPro ~ Circus Park from Shadow the Hedgehog and idk the other one
THEJOSE8000 ~ Left: Oil Desert Act 2 (from Sonic The Hedgehog 4 Episode 2)
Right: I don't now! :( T_T
syxodude91 ~ one side is oil desert zone from sonic 4 episode 2 and the other is circus park from shadow the hedgehog
Pizzajoe15 ~ Shadow the hedgehog circus park is one of them
jandm600 ~ metal sonic theme and oil desert act 2
r543Blitzsonic ~ both music songs sound a bit different than the original but i think that i can hear oil desert from sonic 4 ep 2 act 2 and final chase from sonic adventure 2 (battle)
turbotim33 ~ I can tell the left is Oil desert Act 2 from Sonic 4 episode 2, but I have no clue what's on the right.