Can I splice two different colors of rope light together?

Yes. Simply use a splice and you can connect whatever colors you choose, as long as it is the same kind of rope light.  You cannot connect 12 volt to 110/120 volt, nor 3.36 watt to 5.5 watt.  Standard 2 wire rope light cannot be connected to chasing 3 wire rope light.

For best looking results, you will want to use an invisible splice  and clear shrink tubing. If you choose, you can also use a plastic splice kit.  Be sure your splice connector has the same number of pins as the number of wires in your rope light.  You must use a three pin splice for chasing rope light and a two pin splice for standard two wire rope lighting.

First cut the rope cleanly where indicated by the silver line (18 inch and 36 inch segments). See cutting rope light for details.

Second, slide a piece of shrink tube over one end of the rope light.

Third, insert the "invisible splice" connector pins into both ends of the rope light.  Push all pieces together firmly.

Fourth, slide the shrink tubing so that it covers the connection and use a hair dryer to seal it.