I have both Veg and Flower in the same room, they face each other. I have a black plastic curtain that i roll up when the flower lights come on to improve airflow/heat/etc. and roll back down when the lights go off to block it from the longer light of the veg side. It's been great so far. If anything the veggie's love the little bit of red/orange spectrum from the HPS in addition to the blue spectrum of the Veg Fluoros.

I'd say it's ok to let your lights hit both veg and flower during lights on, but during lights off you better make sure they are separated really well.

just my twin Lincolns.
Skeet.