Those of you who have used Micrografx Designer in the past may have seen the "Line Fill" option in the curve object properties.
While this particular feature is not supported with Corel DESIGNER, you can create multi-color lines of any shape in a few steps with Corel DESIGNER.

To create a 2-color dashed line you can follow these steps:

  1. Create the curve as solid line and give it the intended line weight (width)
  2. Duplicate the curve at the same position (select the curve, then copy (Ctrl+C) and paste (Ctrl+V) it as 2nd object above the original curve)
  3. Make the duplicate a dashed line
  4. set the outline color of the dashed line to color 1 (red), outline color of the original (solid) curve to color 2 (green).

Now you can edit both curves together. You may want to group the 2 curves to make sure they are treated as one object when selecting them on screen.

For editing the curves with node editing mode, you need to select the objects within the group individually. The easiest way to do that is to pick the curves in the Object Manager docker. Expand the group, then pick the 1st curve object. Hold down the Shift key and pick the 2nd curve object in the group.
You can select the Shape tool from the tool box and then select nodes of both curves simultaneously by drawing a rectangular frame around the overlayed nodes.

Both curves will be edited with their shape simultaneously then:

Of course you can create much more complex lines - just explore the various dashed/dotted line types to overlay a solid curve.

One additional tip: To get crisp ends of the individual dashes, go to the "Advanced" tab in the Outline settings in the Object properties docker and select the 1st or 3rd "Line caps" options: