Some strange behaviour I've encountered twice in Excel is that changes made to one sheet would be duplicated on another sheet in the same workbook. The first time, I typed values into a few cells on sheet 1, and the corresponding cells in sheet 2 also changed. There were cell references involved. It was as if there was carbon paper between the two sheets.
The second time, on sheet 1 I copied a formula at A4 over the 1000 cells below it. On sheet 2, a formula that happened to be on A4 got copied over the 1000 cells below it, destroying the sheet in the process.
Does anyone know the cause of this?