In Format Cells -> Borders of a cell, I unchecked "Synchronize", and clicked on OK. But, the cell borders are not dissynchronized. When I go to Format Cells -> Borders of the same cell, the "Synchronize" checkbox is checked back.
It is not checked back, if you make a change in the padding fields. I think it makes sense to keep it like this. People would get angry, if it was changed.