You can now choose to display lines side by side or overlapped for line charts:
Multiple Filters Line Chart Gadget
Multiple Filters Line Chart Gadget (Weekly)
Multiple Filters Statistic Line Chart Gadget
This option is not available in Multiple Filters Line Chart Gadget (Monthly), all lines are overlapped due to width constraint.
Side by side default
If 2 lines happens to have the same values, you can click on the color legend to hide the top (displayed) line and reveal the bottom (hidden) line.