Not trying to sideline this thread too much, but if Phaedrus's interpretation is correct does that mean that mean you can stack multiple body of the sun from spell compendium or multiple pulse of hates from phb2 to cause enemies to take your aura damage multiple times?!
I'm having trouble seeing how PXY's comment pointing up the section on "spells that provide bonuses or penalties" is relevant to our question of spells that "produce varying effects if applied to the same recipient more than once" such as Heroics.
Regarding Body of the Sun, that would at best fall under "Same Effect More than Once in Different Strengths", you'd roll each set of damage, and your opponent would take the highest roll. A better example from that book is Elemental Body, which transforms your body into an elemental substance of your choice and grants abilities based on the choice. Under PXY's interpretation you could become both water and fire at the same time, and presumably you would attempt to extinguish yourself with your own drench ability. Would be fun to watch.