Two senses of mortal and immortal: must die or can die; cannot die or need not die
To make their view on this clearer, they point out that in the state of integrity the first man was mortal in one sense and immortal in another.
A person can be called mortal in two ways, and immortal in two ways. In the first way, a mortal is one who must die; in the second, one who can die. Likewise, in the first way an immortal is one who cannot die; in the second, one who does not have to die.
Latin
II. Verum ut quae sit hac de re eorum sententia melius percipiatur, observant primum hominem in statu integritatis aliquo sensu mortalem, & aliquo sensu immortalem fuisse. Bifariam enim aliquis mortalis dici potest, ac totidem modis immortalis. Uno modo mortalis est quem necesse est mori. Altero modo mortalis dicitur qui potest mori. Et rursum uno modo immortalis est qui non potest mori. Altero modo quem non necesse est mori.