I haven't had an Evolver for a few years. But with an analog ring modulator (and presumably a digital one), it doesn't matter which oscillator is the carrier and which one is the modulator, the sound winds up the same. Ring mod, like multiplication, should be commutative, like you said.
Are you sure the oscillator levels are at 0, so that you're only hearing the ring modulated signal? If either Osc 3 or Osc 4 are sneaking in there, that could explain your difference.