Doppelganger-generating device

"Doctor, you finally completed the device!""Congratulations—all your hard work has paid off.""Hey! I'm over here!""Wait, there are two of you now, Doctor?""The one you've been talking to this whole time isn't me.""It's an illusion the device generated.""I see, so that's what happened!""Hey! I'm over here!""Wait, there are two of you now?""The one the doctor has been talking to this whole time isn't me.""It's an illusion the device generated."