It was late last night and I was tired when I posted and I see that my notation wasn't particularly clear, so I'll try and clarify what I meant.

The first tune moves between C major and C mixolydian, the 7th switching between B and Bb. It's not uncommon to find this type of tune, a major with inflected 7th, the 7th being one of the notes that people vary a lot.

The second tune is a Bb hexatonic tune, the 4th being missing. This is the intersection of Bb major and Bb lydian, the two scales being identical except for the 4th degree (here, Eb in Bb and E in Bb lydian). (It's possible to derive a sequence of hexatonic scales from the modes by arranging the modes in order, where each differs by only one note from the previous. This would start: lydian, ionian (as here - 4th note differs); ionian, mixolydian (7th note differs) etc). So the hexatonic scale in tune 2 is Lydian/Ionian.

I hope that clarifies things a bit.

Mick