evil twin
1. A malignant, treacherous, and/or malicious counterpart of a person or thing. Our competitor sells similar products, but they manufacture them in sweatshops—they're like our evil twin.
2. In telecommunications networking, a hidden wireless access point located near a legitimate one, used for the purposes of eavesdropping or diverting sensitive personal information. I know you think I'm just a conspiracy theorist, but the government is using evil twins to listen in on digital communications between people all around the country!