Section 15 of the principal Act is hereby substituted for the following section:

"15. Restriction on issuing of more than one prospecting permit or mining authorization in respect of same mineral and land

No prospecting permit or mining authorization shall be issued in respect of any mineral in respect of land or tailings, as the case may be, if a prospecting permit or mining authorization has already been issued in respect of such mineral and land or tailings, as the case may be, unless the [regional director] Director: Mineral Development is satisfied that such first-mentioned issuing will not detrimentally affect the object of this Act in relation to optimal exploitation of minerals [safety, health] or rehabilitation.".