Mozart 36, Note help needed..

[Ken Smith]

In Moz. 36, 2nd movement, bar 48, there is a B nat. 2nd half of the bar. The same line in bar 46 has a Bb. Two separate recordings/Utubes of the Vienna Phil. they play Bb BOTH times the first time thru. Several bars later, bars 60 and 62 these phrases are repeated and they play the written parts, Bb and the B nat. as written. I have music from 2 sources and they both have a B nat. written in bars 48 and 62. Was this just Vienna that changes that note or is all the music and scores wrong?

[Joshua Phelps]

Maybe they play some different arrangement with slight variotions. Always seems like music from Europe is different in some small way to copies that have been arranged in the states.