help on using the same note in a scale

When using scales and a C flat and a B come up do you play the B twice or just once to accomodate for the same note? What about the E's and F's, do they follow the same rules?

I don't really understand your question, but usually if you have something with a C flat in it any B will also be flattened. Anyway, it is very rare to play something with a C flat in it, because it is only called that in certain circumstances. Any normal time it is just called a B. Is this music you are reading, or are you just practising scales?

Just practicing scales. When I follow the rules on how to form modes I sometimes end up with B, and then a C flat. I was just wondering how you would play that and keep the intervals correct. For example: When I wrote out the mixolydian mode from the C scale (makes it a G mixolydian, right?) I came up with G A BC D E and F flat. How would I change it with out messing up the intervals.

Hmmm, it seems as if you are constructing scales incorrectly, though I'm not exactly sure where the problem lies. If you play a G mixolydian scale, you are playing G A B C D E F, as G mixolydian uses all the notes from the C major scale. Note that as the G major scale normally has an F#, when you flatten that you get an F, not an Fb. You never have a scale that has the same note twice, even if they are called different things. Remember that keys other than C major have sharps or flats in them; for instance, G has an F#, and D has both an F# and a C#. This is so the intervals stay the same. The intervals of a major scale is Tone, Tone, Semitone, Tone, Tone Tone, Semitone. That is, a tone from C to D, a tone from D to E, a semitone form E to F, etc. If you number the intervals in a major scale, you get 1,2,3,4,5,6,7, upon which all other scales are based. A mixolydian scale has 1,2,3,4,5,6,b7. However, that doesn't mean that the seventh note is necessarily flat, but flattened form what it was. If you have the G scale, you flatten the F# to an F, not make the F note a flat. Is this where your problem lies.
Hope this helps.

Thanks for the help. I was flattening notes like F sharp to an F flat when I shouldve flattened the F sharp to a F. Thanks for helping me out.

The only time you're likely to use things like C flats is when you want to play somehting like a Bb Locrian scale. The locrian scale has a flattened 2nd, so you need to flatten the C to a Cb. You don't call it a B because you already have a B note in your scale (the root, Bb). In scales, you never have two notes in the scale with the same base name – ie. you can't have a Bb and a B, or a Db and a D#. this is why some scales can get to things like an Ebb – in other words, a D – to keep it like that, but it's rare that you play scales like that. Glad I could help you, it was tough working out what was going wrong, but I agree it can get pretty confusing. Remeber, you flattenthe note, you don't make it a flat.