Is your employer okay with soft copy of your license? If so, then you can just take a copy of US license that you have and share it with your employer. Even though Canadian DMV takes your US license, it doesn't do anything revoke it. Your US license continues to remain active even after they take it. If you physically need US license, you could just report your license as lost in US DMV and get a new copy to your US address. Other than doing this, I don't see any other way to keep both country license if you are living in Canada.
I am not sure what Canadian citizens do, but my guess is US DMVs don't take back the Canadian license from the applicants while exchanging and it let it be with them. That way, it might be possible to keep license in both countries.