Two unconditioned dhammas?
Space is one of the 24 kinds of derived-materiality (UpadayaRupa), which is one of the 2 kinds of materiality (the other is primary-materiality, BhutaRupa, which is composed of the 4 elements of earth, water, fire, and air). They're all conditioned dhammas. Only Nibbana is the unconditioned one. Further info. is available at Vism.XIV.34