Andre - the problem is both of your lines are pointing to Axis 1
In the DOM this is all in the same class - see below:
If you change your second line to go to Axis 2
Then you can better specify which color goes to which line via the axis:
g.v-m-main g.v-m-plot g.v-markers.v-datashapesgroup g.v-axis1 path.v-datapoint.v-morphable-datapoint:nth-child(1) {fill: green;}
g.v-m-main g.v-m-plot g.v-markers.v-datashapesgroup g.v-axis2 path.v-datapoint.v-morphable-datapoint:nth-child(1) {fill: red;}
See below:
