Why would it be any different if you had applied for the Edge first then the Platinum as both earn Ascent points.
From what I've read from others, anecdotally, sounds like it is possible to get the bonus points for the same program (i.e. Ascent, in this case) if you 'upgrade' to a higher tier of card in the same program - i.e. from the Edge to the Charge, but not if you 'downgrade' (i.e. Charge to the Edge).
@Blueythecat, agree this is a good long term card with excellent day to day points earn, so one for the long haul.