For this example I have used the 12 Roses Silhouette by Toucan Scraps.
First create 2 rectangles the same size side by side one in "colour 1" and the other in "colour 2"
Then place the silhouette centrally on top of the rectangles, resize if needed, and recolour it "colour 1".
Copy the silhouette and place it directly on top of the previous silhouette. Recolour this one "colour 2"
Select the top silhouette and crop it along the join line of the 2 rectangles.
Print and use in your project.