create 4 data series with say 10 values each make the first series a sequence of dates =today(), =A1+1, etc. and the second to fourth series some small random numbers.

select the series
insert chart
select line plot
select Use first series as shared abscissa
show sample: the first series is _not_ used as shared abscissa
forward:     the first series is _not_ used as shared abscissa
             it is in fact shown asa separate series.


Note that if I delete the first series (of dates) and add it as (Labels) to the new first series, it is used as common abscissa, except that only the first value is formatted as a date, the remaining ones are numbers.