I think that would make it look more natural. You might want to take the darker shade and apply fine, thin lines in feathery strokes starting from the center line; then take the lighter shade and same application spread out above and below the browline center.
Try using a product that has two shades to work with or a wax and powder. This will allow for more range in terms of color payoff.
I love Benefit's BrowZings as it has a tinted wax (which can be used on it's own) and a colored powder. The kit comes with two brushes and a mini set of tweezers. I still like to use a full sized angeled brow brush (Smashbox makes a great one) with the kit as the tiny brushes aren't as stiff.
Smashbox's BrowTech is also another product that's fab, this one comes in a wider range of shades, has an untinted brow wax, and two colored powders.
Keep a spoolie brush on hand (clean mascara wand, available at beauty supply stores) to comby through and soften product after you've applied.
I agree with the previous recommendations.
I also love the BrowZings from Benefit. I have some spare areas, but really hate the fussing with brows as you can tell when they've been overworked.
You may want to try the Benefit Speed Brow. It's a universal color that tints only and shapes. It's super fast and natural looking.
Yes. Anastascia makes excellent duotoned brow powders. You would use the darker of the two shades toward the tail of the brow and at the arch. As for the rest of the brow, gently fill in with the lighter shade and be sure to blend. Another way to highlight and accentuate the brows would be to add the Anastascia highlighting pencil in matte Camille under the eyebrow to make your eyebrows stand out and disguise new brow growth!