Urethral duplication is a rare urogenital anomaly, especially in females. We present the case of a preterm female with various congenital anomalies, hydrocolpos, and a persistent interlabial cyst, later found to be secondary to urethral duplication. At age 2, cystoscopy and VCUG confirmed a duplicated urethral tract. Surgical resection of the accessory urethra and genitoplasty were performed successfully. Postoperative recovery was uneventful, with excellent cosmetic and functional outcomes at follow-up. This case highlights urethral duplication as a rare but possible differential diagnosis for interlabial cystic lesions in females, particularly when associated with fluctuating size and underlying urogenital anomalies.