Well you're never technically baptized "again." The Orthodox Church recognizes only one baptism for the remission of sins. What you will find is that some bishops will only chrismate individuals who have had a Trinitarian baptism. That is not a recognition of the heterodox baptism on it's on right. Rather, it is saying that Orthodox chrismation completes and fills the previous heterodox baptism with grace.
Any Orthodox bishop is well within his right to baptize anyone wishing to be received into the Church who has not received an Orthodox baptism. That being said, what happens to you depends on the practice of the particular jurisdiction into which you are received and the practice of the bishop.