Drag two variables together to Y, drag another variable to X. In contexual menu (right click on Y) pick "Move Right" and select one of the variables. Then it is possible to independently select any graph type for the left and right Y variables.
JSL example:
Open( "$ENGLISH_SAMPLE_DATA/Big Class.jmp" ) << Graph Builder(
Variables( X( :age ), Y( :height ), Y( :weight, Position( 1 ), Side( "Right" ) ) ),
Elements(
Line( X, Y( 1 ), Summary Statistic( "Mean" ) ),
Bar( X, Y( 2 ), Summary Statistic( "Mean" ) )
)
);