SUMIF Criteria Issue

XL, and SUMIF, will implicitly coerce the criteria - and interpret as a number - XL operates to 15 significant digits, and thus they're seen / interpreted as being the same.

You could revert to less efficient SUMPRODUCT which will not perform the implicit coercion, i.e. below would return 0.0068 for both

=SUMPRODUCT(($B$2:$B$3=$B2)+0,$A$2:$A$3)

Hi XLent,
Thank you for your explanation and alternative solution.