Marcelle King, from Poole, was left with permanent sinus problems and a drooping brow after Melin administered injections in 2013.
Carol Kingscott, from Bristol, suffered severe swelling and burning to her face and was also left with a drooping brow after being injected by him in 2011.
In both cases the women had suffered no ill effects after a first course of treatment, but had severe reactions after going back for a free “top-up” offered by Melin.
The prosecution case at trial was that each woman only consented to the treatment because he had lied about his medical qualifications and training.
However, Mrs King gave evidence that Melin had only told her about his qualifications at her second appointment, moments before injecting her.
Quashing his conviction in relation to Mrs King, Mrs Justice Simler said Melin had made no claims about his medical qualifications before the first treatment.
The judge said: “She was already in the treatment room poised for the second treatment before any representation was made by the appellant as to his medical qualifications, even taking her evidence at its highest.
“It is difficult to see how the statement he made 30 seconds before the injection went in on the second treatment can have had any operative effect on her decision to take up the second treatment.