There are a few plot holes in the theatrical release of Terminator 2 that are resolved in the special edition of the film. How did John know which version of his mother was real, and which was fake?

Terminator 2 stars:
Arnold Schwarzenegger as the Terminator (T800)
Linda Hamilton as Sarah Connor
Edward Furlong as John Connor
Robert Patrick as the T1000
Earl Boen as Dr. Silberman
Joe Morton as Miles Bennett Dyson