Originally Posted by
LondonElite
Hmm, my guess is that he would just travel on his new US passport, and not show the old one. What do others think?
Simple - apply for a visa.
It does not really matter what was the exact reason for the denied entry. If OP is serious about this travel, then OP should seek assistance in official channel. Applying for a visa is the only way to resolve any doubt about OP's admissibility.