'99 Tahoe mirrors

I have a '99 Tahoe. Something has happened to the driver's side mirror, that when you use that mirror everthing appears doubled (at night) or has a shadow (during the day). Any ideas about what is wrong? Could the mirror have somehow gotten warped?

The drivers side mirror has a defroster in it; the seal broke and the fluid leaked out causing what you are experiencing. You need to replace the mirror. You can purchase the mirror and housing or just the mirror. It's an easy fix.