Can one output from a Frog Juicer be connected to more than one turnout?

Yes, if you are sure that:

1. the frogs will act in concert. If one frog is one polarity, then all other frogs should be the same polarity, as with consecutive frogs in a double-track crossing.
   - or -
2. there will only be a single locomotive on one of the frogs at a time. For example, an industrial spur that a single locomotive will only ever switch.

If two locomotives short a single output by chance, it will shut the booster down, but it won't cause permanent damage.