Not sure what you mean by "more equal degrees of tension" Tension is measured in pounds, or pressure (taking the area of application into account).

The grade or type of steel does not determine the stress that is on it.

Stress=pressure=pounds per square inches = pounds of force divided by the cross sectional area of the smallest part of the spoke.

With different types of spokes, you could, in theory, tension each spoke till it was equally stessed as a percentage of its maximum rating. But why would you want to go to so much trouble?