I don't think it's just Greek - phonetically the B and V sounds are close, so a language that doesn't have one will comfortably use the other, and one might change into the other over time as well.
For instance, the Hebrew names we know in English as
Abram and
Deborah seem to be
Avram and
Devorah nowadays - though I don't know if that's what they were in Hebrew all along, or if it signals a shift in pronunciation.