Copying what? The data packets? The IP address? The MAC address?
What encryption are you using? WPA2-PSK? Is the SSID being broadcast by the WAP? Is MAC filtering enabled?
While none of those are foolproof, they make for a pretty secure environment. I’d be more worried about someone yanking my supposedly sensitive printout right off the network printer before I got there.
For that, you use .45 cal security... '-}