It becomes "fake" stereo at 2:12. Only the first 2:11 has ever been released in true stereo. Of course during the fade-out the sound is panned from side to side, but the recording itself is "fake stereo". Fake stereo was a dumb idea from the 1960's. Take a mono recording, split the signal, giving one channel a lot of high end, the other channel more low end. The fact that the 2nd half of WALRUS is NOT in true stereo has been documented in many sources, including Mark Lewisohn's THE BEATLES' RECORDING SESSIONS.