You can only rotate ONE antenna (Yagi or whatever) at the same time, so you need only 1 rotator for all beam-antennas.
And different Yagis for the same band makes normally no sense. It would be better to use (for example) a 5-el Yagi and a Cardiod (or Quad) for one band. And both are turned into the same heading, depending on which antenna is currently active, of course.
73 and good DX from Jörg :-)
JO31ok
Bochum / Germany