I wasn't sure if this would be the right forum to post this but there's a slight bug in excel, if you have 2 or more columns merged and you paste special -> formula into those merged cells it will write the value to the individual cells instead of giving you an error or writing to the "single" merged cell. This can cause your sum() formulas to count the values in the merged cell twice.
I like to think the lesson here is to avoid having formulas/computational values in merged cells, but I may be slightly biased here.
I like to think the lesson here is to avoid having formulas/computational values in merged cells, but I may be slightly biased here.