Hi Jonathan,
You are right, the page break is inserted twice since both PageBreakAbove->True and PageBreakBelow -> True are set for the PageBreak cell (WRI guys, to you attention, you need to remove one of them).
One immediate solution you may use, is to insert a page break after the cell you want to, as an option to that cell.
Let the cursor be in that cell, than Menu Format->Option Inspector (CTRL+SHIFT+O or CMD+SHIFT+O for short)
Set the PageBreakBelow to True, and you are done
yehuda