For our 1098 for mortgage interest statements, we have always put N for box 7 even if the address of the property was the same as the Payer's address and then put the property address in box 8 (I have not idea why, at some point that is what we were told but now we are questioning it). When I looked at the instructions, it states "If the address of the property securing the mortgage is the same as the payer's/borrower's mailing address, either check the box or leave the box blank and complete box 8. If the address or description of the property securing the mortgage is not the same as the payer's/borrower's mailing address, complete box 8." So according to the instructions, box 8 is to be completed with the address of the property securing the mortgage whether it is the same as the payer's/borrower's mailing address or not. So my question is, does it really matter what is in box 7?

No - I think you are misreading that. If you check the box in 7 - then you leave Box 8 blank. If you don't check the box in in 7, then you must complete Box 8.