you don't use alternative measures to do this, but instead create an inline table as follow:
load * inline [
now, add this new Measure filed as a fitter in ur dashboard;
in ur chart, as measure:
if(MeasureID=1, sum(Measure1), sum(Measure2)) , with that, if u select from ur filter, YourFirstMeasure, u'll have sum(Measure1) etc..
same approach to build the min and max values with if conditions
and u can always make ur chart clearer; by adding a condition in ur adds on, count(distinct MeasureID)=1
with that, u force a selection of one measure only !
and add this information in your chart title, for example
=Measure&' by year'
with that, u'll know, what measure u're using in the chart..
and maybe same approach in the expression label
hope that was clear..