Usually - yes. It's called a "heat leak" rad. The idea is that any buil up of excess heat in the boiler can be leaked away to save the system from overheating. It's usually put on the landing - somewhere precise control is not needed.
Having said all that - I think we'd better wait for a friendly plumber to walk by - because - I don't know if its still essential with today's systems.
i agree with builders mate and in addition you shouldn't have a radiator with a thermostatic valve in the same room as a wall thermostat as the 2 will conflict with each other.