Because the axis is DateTime type, values just run linearly and hence having two dataPoints with different date/time/value is not possible.
I can suggest you a way of emulating it though.
1. Use label to set same values (monday, tuesday, etc) for both the series so that they get drawn one on top of the other. Don’t set x values.
2. Set toolTipContent for individual dataPoints – as required
And, is-it can to display a vertical line in the chart When a mouse over a date in the AxisX?
If you meant a vertical crosshair, it is not possible yet. Its planned for v1.5