Who is the Real 8-Legged Muto?

It is most likely the one without the wings. The wings on winged Muto seem to take the place of two of the multiple legs.

I would hazard a guess that it's the one with eight legs! No seriously, the other has a set of wings and six legs! 

If you did not read the imdb review or any other here are the facts (SPOLIERS):

-There a two Mutos, both are a couple and build a nest.

-THe Male is the flying one, and it is a shorty guy: is the Muto from Airport scene.

-It was declared the female is bigger than the male, she is the eight-legged Muto and probably matches Godzilla in size.