Solid colour using track matte - can I make it independent?

Hi,

I have some footage of someone moving.  I have used the Object Matte Tool to isolate the person moving, then placed a solid colour layer underneath and selected the top layer as track matte.

This has worked very well.  I now have a solid colour replacing the person on a transparent background.

I would now like to play around with this, mirroring and adding echo etc.  Can I/should I make the solid layer independent of the tracking layer?

Thank you.