This will depend on each centre. The only time we recommend or allow this is when a child and parent float together to help the child feel familiar and comfortable with the unique environment before they start their journey.
Otherwise, floating is all about you and enhances your experience and sensory atonement. Give yourself the time to recharge and reconnect. If someone else is in the tank, you will feel and hear every breath, which impairs your ability to deeply relax and allow your brain to switch gears. Remember, you are here to reduce external sensory input. But you are an individual and it is your experience. Make sure you call the centre before, find out your options and see what style and size the tanks are.