The painfulness of the decision is also a form of disutility that has to be balanced against the difference between the charities though, which was the point of my original comment. If the difference between the values of the donations, when adjusted for the species involved, is less utility than the amount you personally lose from agonizing over how to apportion your donation, splitting it may result in higher utility overall.
Obviously, this is heavily dependent on how large the utility differences between the top charities are; if it weren’t, my comment about discounting the suffering of less intelligent species wouldn’t have been relevant.
The argument was explained in the sentences immediately preceding the one you quoted.
The painfulness of the decision is also a form of disutility that has to be balanced against the difference between the charities though, which was the point of my original comment. If the difference between the values of the donations, when adjusted for the species involved, is less utility than the amount you personally lose from agonizing over how to apportion your donation, splitting it may result in higher utility overall.
Obviously, this is heavily dependent on how large the utility differences between the top charities are; if it weren’t, my comment about discounting the suffering of less intelligent species wouldn’t have been relevant.