best is to find someone else, how can he act in the best interest of you if he is also acting for the other party.
also if he had made an error, there is no independent party to look out for you.
And if he was honest, he should have point that out to you for the fact that he also act for both party not you who have discover it.
what is the formal signed offer, is it the conract? or to the real estate agent that you are making the bid? the conveyancer's deatils should appear on the front of COS.
