Hmmm why the discrepancy? Compassion.com has been around a long time... Hope it is just an error in number lookup or accounting.
Theymos point about not having multisig address is a concern if Rob has a catastrophic malady. There's no backup if no one else has the private key.
The reason for the discrepancy is not known yet but I am sure Rob will sort it out. Again, I am not doubting the legitimacy of BBP or the number of children sponsored. I just want to make sure the house is in order first as it will be easier to convince others.