Sharing a vent

I am installing an extractor fan in my shower room and was wondering if I fitted one in the bathroom (which is next door) and brought ducting through wall could I use a tee piece and just have one external vent.

If you want the smells and damp air from one bathroom going into the other - then yes

The vents are not directional/one way.

A friend of mine said ( he lives in a flat ) that he has an extractor fan in his shower room but instead of a vent to the outside which apparently can't be done, he has a little tank type thing in his bit of loft space that collects the steam and he empties when full. Had anyone ever heard of this type of system. Almost sounds like a tumble dryer sort of thing. Would it work for a shower?