Complete ureteral duplication is uncommon and occasionally associated with ureteral stone obstruction. Even rarer is ectopic insertion of a ureter into the urethra. We describe a case of a 75-year-old man with a history of robot-assisted laparoscopic prostatectomy and complete unilateral duplicated collecting system with a ureteral stone obstructing an ectopic ureter inserting into the urethra. The stone was effectively treated using ureteroscopy with laser lithotripsy. Ectopic ureters can be located in any of the Wolffian duct structures, and can perhaps be relocated iatrogenically secondary to bladder neck reconstruction during a prostatectomy. This should be kept in mind when performing ureteroscopy on this patient population.