graham,

the closest to what? When you say "the criteria is showing up twice", I
understand that in the date column your lookup value appears twice. If
so, then SUMIF() is designed to get you the sum for this date, no
matter how many times it appears.

So, if the two days are the same, does closest mean "most recently
entered (therefore further down the worksheet)"?. Is there another
column for which we want the highest value for the given date?