I want to do the following:

If the cell C2 from file A is equal to cell C2 from file B (Contact person)
AND
cell D2 from file A is equal to cell D2 from file B (Company)
then
copy the content of cell N2 from file A to cell N2 in file B (Notes)

I created a spreasheet of contacts for a co-worker. I gave him a copy of my
spreadsheet. When he writes notes (cell N2) in his spredsheet, I want to see
them in mine. The IF formula is just to check for possible errors that can
occur if he alters his spreasheet in such a way it won't match mine anymore.