An am assuming the x-values for the two sets of data are not the same.
If they are then there is a simple solution
Otherwise:
An other way (may not be much quicker)
Make chart with first data set
Copy second dataset
Click chart
Use Edit | Paste Special - New data series - first column has x-values

For those thinking of giving you a VBA solution for the 100 charts:
1 - data is on different sheet?
2 - same layout (number of points) in all cases?

best wishes
--
Bernard V Liengme
Microsoft Excel MVP
www.stfx.ca/people/bliengme
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"DSO" wrote in message
oups.com...
I want to create a trajectory plot, being that each trajectory is a
set of XY pairs (2 columns).

For that I've been using the scatter plot, however if I select more
then one pair of XY columns Excel creates multiple Y series using the
first column as X axis values for all the series. So I have been
forced to add series one by one in the Select data menu.

Since I have hundreds of trajectories to plot, I'm searching for a
more practical way to add series to the graph.

I would greatly appreciate any help on this issue.