(a) a determination would result in an acquisition of property; and
(b) the determination would not be valid, apart from this section, because a particular person has not been sufficiently compensated;
the Commonwealth must pay that person:
(c) a reasonable amount of compensation agreed on between the person and the Commonwealth; or
(d) failing agreement--a reasonable amount of compensation determined by a court of competent jurisdiction.
(2) In assessing compensation payable in a proceeding begun under this section, the following must be taken into account if they arise out of the same event or transaction:
(a) any damages or compensation recovered, or other remedy, in a proceeding begun otherwise than under this section;
(b) compensation awarded under a determination.
(3) In this section, acquisition of property has the same meaning as in paragraph 51(xxxi) of the Constitution.