5In a case in which the fee simple in the coal or mine, or the term of years under a coal-mining lease thereof, was vested on the valuation date in a person other than the person in whom the fee simple in land supported thereby was then vested, and any right to withdraw support from that land, other than a right granted by a working facilities order, was then annexed to the coal or mine, there shall vest in the Commission therewith a right to withdraw support from that land similar in all respects, whether as regards terms, conditions, extent, duration (save as in this paragraph provided) or otherwise, to the said right that was then annexed to the coal or mine :
Provided that, where the fee simple in the coal or mine and the fee simple in land supported thereby was vested in the same person but the term of years under a coal-mining lease was subsisting in the coal or mine and a right to withdraw support was annexed thereto, the duration of the right that vests in the Commission shall extend to the whole of the period during which any coal to which the first-mentioned right was annexed remains ungotten.