Toffee's physical form is a Septarian/lizard monster, but the immortal part of him is the immaterial consciousness that allows him to regenerate any body he occupies. Thus:
The two halves would come back together on their own to form the complete Toffee, and any missing pieces would be regenerated once Toffee is mostly whole.
The "real" Toffee wouldn't be either half but the spirit driving both pieces to reconnect. One both pieces are reconnected then the "real" Toffee is also Toffee's physical form.
I should know, I am an expert in unrealistic fantasyworld lizardman regeneration.