Can Motion 5 replace a green screen and blue screen in the same shot?

Question

Can Motion 5 replace a green screen and blue screen in the same shot? I would like to replace a green screen with one image, and a blue screen with another.

Answer 1

Fox gives a good example for keying green & blue (or any other color)  from the same shot. I'd suggest doing a few things to get better accuracy.
First, the motion keyer always removes the color it detects the most of by default (blue/green). You can override this by setting the Strength parameter to zero, then use the Color sample tool to select the color you want. The advantage is motion will do a good job of targeting only the hue (color) that you want to remove and set an appropriate starting softness.  It also will remove spill based on this color.  Looking at Fox's example movie and the shot, I'd approach the same shot this way:
Remove the Blue
1. Apply the keyer and set the strength to zero.
2. Use the Sample Color tool and select the blue (or other color) to be removed.
3. Decrease the spill level (if needed). In Fox's example the spill from the blue glasses is going to be minimal, especially compared to the green screen, your shot may need different adjustments. Only de-spilling what you need to will give you more accurate color right away and minimize additional color correction that might be needed later.
4. Use the Color selection tools (Chroma wheel/Luma bar) to fine tune.  Ideally you want a minimal tolerance, the inner selection, with a nice fall off, the outer selection. Try with the Scrub boxes setting first, then switch to manual if you need more control. Again see Fox's example.
Remove Green
It's the same as the blue, you could apply the keyed to the same clip or a parent group, at this point it's many user preference.
With these techniques you can remove any color from a shot or create a mask based on a color. BTW, as you are learning to use the keyer I'd highly recommend  having the Color Selection open so you can see the graphs.  These give you real time feedback as you make selections and changes with the Strength, Refine and Color selection tools.  Watch what happens as you make selection or changes, sometimes the problem area is actually in the brightness not the color, or the softness may change  more than the tolerance selection.  Observing what is happening in these graphs will help you figure out wha to change and speed things up.