Background Diphallia is a very uncommon malformation, and glans duplication (GD) is its rarest form. In this last group, patients normally present with esthetic/sexual complaints or obstructed voiding late in life after pubertal genital development. Associated malformations are uncommon and relatively mild in those cases. Methods After a case presented, we present herein an extensive review of GD, as the disease is rare, and there is very little about its treatment and there are diverse approaches to address the condition. Results After an extensive review of the available literature, we carefully analyzed each published case to describe specific aspects of their clinical presentation (age, main complaint, voiding/urethral problems, and individual anatomy) and treatment. Conclusion This review allowed us to propose a new classification for diphallia into four groups (true diphallia, hemiphallus, pseudodiphallia, and partial duplication), considering embryological, anatomical, clinical, and therapeutic implications (see Fig. 1). Glans duplications present as esthetic/sexual cases or show abnormal voiding patterns caused by urethral associated abnormalities. Reconstructive techniques may be simple (resection of a hypoplastic accessory glans + urethra) or relatively complex (glans and/or urethral reconstruction).