The triplicate A2 variant is one of several common anomalies of the anterior cerebral artery. An anterior communicating artery aneurysm with triplicate A2 variant in close proximity to the aneurysm neck is challenging to treat due to potential unilateral/bilateral corpus callosum or parietal lobe infarction. Alternate simultaneous bilateral carotid angiography can differentiate triplicate A2 branches through time-difference alternate injection of contrast into the carotid arteries bilaterally, which can enhance anatomic understanding of complex anterior communicating artery aneurysms during complex endovascular treatment. In this case, a complex aneurysm with an associated triplicate A2 variant was treated successfully with Y-stent−assisted coil embolization using alternate simultaneous bilateral carotid angiography.