If two Pokemon are both holding an Exp Share, how much experience will they each get?

Yesterday I posted a question about the Exp Share in the Pokemon games and I got some good answers, so now I have another one. If my party is headed by a level 100 Charizard, and I have two Exp Shares, one held by a level 55 Venusaur and the othe held by a level 51 Blastoise, will they each get half the experience or will they only get a quarter of the experience? I would think the latter, since half the experiece would again need to be split up by 2, right?