Actions:
1.open cals, create a empty file, merge B4:B9,  merge C4:C9, merge E4:E9, merge
F4:F9, now there're 4 merged cells: B4,C4,E4,F4.
2.set borders(left ,right, top, bottom) of C4 to 1.00pt weight, set borders(left
,right, top, bottom) of E4 to 1.00pt weight.
3.save it as "mergedBorders.xls" in type "Microsoft Excel 97/2000/XP(.xls)", and
close file.
4.re-open "mergedBorders.xls", and the borders are confused: 
    for C4: only the top 1/6 borders are left, and others missing.
    for F4: 5/6 from the bottom, which are not supposed to have borders , are of
solid line border.

If save file as "Microsoft Excel 2003 XML(.xml)", and open it by APIs, and do query:
------
XPropertySet cellPropSet = (XPropertySet) UnoRuntime.queryInterface(
XPropertySet.class, XCell);
BorderLine left = (BorderLine) UnoRuntime.queryInterface(BorderLine.class,
cellPropSet.getPropertyValue("LeftBorder"));
BorderLine right = (BorderLine) UnoRuntime.queryInterface(BorderLine.class,
cellPropSet.getPropertyValue("RightBorder"));
....
------
And the border lines have no problem, but after saved using
XStorable#storeAsURL() with option "FilterName"="MS Excel 97", the same confused
borders appear just as described in front.