Background <p>Gallbladder duplication is a rare congenital anomaly resulting from abnormal bifurcation of the caudal bud during embryogenesis. It may cause diagnostic and surgical challenges. Classification systems of gallbladder duplication are based on cystic duct anatomy. Though often asymptomatic, it can be associated with complications such as cholelithiasis.</p> Case presentation <p>We report the case of a 22-year-old North African male presenting to the emergency department with a left renal colic episode. He complained of left lumbar pain with typical radiation and no other associated symptoms. The patient has a medical history of myasthenia gravis and major depressive disorder. Physical examination revealed left lumbar and iliac tenderness without any other notable findings. The patient was initially referred to the radiology department for a computed tomography scan to investigate potential renal colic and rule out a surgical emergency. The computed tomography scan identified a nonobstructive left renal calculus and a duplicated gallbladder. An abdominal ultrasound was performed for further evaluation, confirming the gallbladder duplication and ruling out gallstones or cholecystitis. To obtain better visualization of the biliary tree and assess for any additional anatomical anomalies, magnetic resonance imaging with magnetic resonance cholangiopancreatography was conducted. Magnetic resonance cholangiopancreatography confirmed a type H gallbladder duplication.</p> Conclusion <p>Diagnostic methods, including ultrasound, computed tomography scan, and magnetic resonance imaging, help identify gallbladder duplication. Magnetic resonance cholangiopancreatography is considered the gold standard for detailed biliary tract imaging.</p>