When do additional power uses stack ongoing effects?

So: FF5 Wraith's power says "Draw a card.  Until the end of your next turn, whenever you draw a card, you may discard a card.  If you do, another player draws a card." If you activate Clandestine Funding multiple times in a round, she gets multiple opportunities to discard and give a draw to someone else each time she draws.  2 Clandestine Fundings means 2 chances to discard, 3 is 3, and so on.

Malpractice Medico says "Until the end of your next turn, the first time each hero target would regain hp each turn, Dr Medico deals 1 target that amount of energy damage instead."  Activating this power multiple times does not trigger multiple instances of damage the first time each hero is healed in a turn.  

Why is one one way and the other the other?  I can't parse it from the rules.

I was going to say it's because Wraith's says "whenever" versus Medico's saying "the first time," but thinking about it more, I'm not convinced that's it.  Now I'm puzzled too.

The key, I think, is 'instead'. You can't replace the regaining of HP twice, you can only replace it once.

So... things go in the order they entered play as per usual, but because it's "instead" by the time the later-entered Malpractice looks at the first time the hero gained  hp it's already been transformed into something else and it can't see it?  I can see that being valid, but I wouldn't have bet on it ahead of time.  Or, if I did bet on this interpretation, I might have also bet that the next heal would have triggered the next Malpractice, because by the time it looked at the healing it would no longer be healing and therefore it would still be looking for its "first" one.

Ah, well.  Still stuff to learn after years of playing, not too bad, SotM!