So it does, I wasn't expecting that !
The only way I can think of fixing this is to reformat your source data a little.
So if you are starting with data like this . . .
..............Col A........Col B..........Col C
Row 1.....X Axis........Series 1......Series 2
Row 2......A.............1...............5
Row 3......B.............2...............4
Row 4......C.............3...............3
Row 5......D.............4...............2
Row 6......E.............5...............1
Reformat it to something like this . . .
..............Col A........Col B..........Col C
Row 1.....X Axis........Series 1......Series 2
Row 2......A.............1...............
Row 3.....................................5
Row 4......B.............2................
Row 5.....................................4
Row 6......C.............3................
Row 7.....................................3
Row 8......D.............4................
Row 9.....................................2
Row 10.....E.............5................
Row 11....................................1
See the difference ?
I've tested this and it does work.
If you don't like the X axis labels being too closely associated with one or other of the data series, try adding more intermediate rows to re-position the labels.