During the summers, AF has, in fact, two (2) daily flights. AF 332 and AF 322 respectively, in part because of the SkyTeam alliance. Once the winter skeds start, the second daily arrival is not operated on Tuesdays or Wednesdays.
I did do some poking around on the AF site and for some reason on 8 Sept., flight 332 was cancelled and flight 322 utilized a 744, presumably to accomodate the pax from 332. Perhaps Jtdieffen, you saw a 744?
FYI, on the 5th of Sept, they used a sole A343 for flight 332. And yes, the A330-200 will come to BOS when AF receives them.