Artificial Double Tracking (ADT) without time delay?

A synch analog copy of the vocal is rerecorded and then added (mixed with the 1st generation master take). Example, on Tezcatlipoca - Ira, George, firtsly the vocal and DX200 drum loop was recorded on Tascam porta one. Then when overdubbing bass and synth (micrKorg) strings, by newbe mistake the vocal had been transfered too on the strings or bass track. This possibly makes the vocal louder or standing out as observed by Vicky while listening to an mp3 transfer of the session cassette where on the particular balance (mix) strings are spontaneously added or remomed.