We can distinguish behavioral zombies, which just act like a person but are not conscious, from physical zombies, which are an exact physical duplicate of a conscious person but are not conscious.

For instance, people have reported doing all sorts of things while unconscious while taking the medication Ambien. They may be behavioral zombies, in the sense that they appear fully conscious but are not, but they aren't physical zombies, because their brain is physically different from a conscious person's (e.g., because of the Ambien).

The existence of physical zombies requires denying materialism: you need some sort of magic stuff that makes ordinary matter conscious. But even though materialism is true, it's entirely possible that you are a behavioral zombie. Once neuroscience is advanced to the point where we understand consciousness better, we'll be able to look at your brain and find out.