There are three fingerings for Bb on saxophone. Depending on the situation (key signature, notes before and after) a particular fingering may be easier in that context. What happens is that a certain Bb fingering lets you move less and be less likely to have a messy connection.
It’s good to have the ability to play all of them. Relying on only one will limit your saxophone technique.
||“Bb with ‘bis’ key”
||“Bb with F fingering”
Thanks to Bret Pimentel for his fingering software.