Benign duodenal tumors are less common than their malignant counterparts. When it comes to duodenal mass or wall thickening causing obstruction, we tend to view it as malignancy. In the following sections, we describe a 40-year-old man who underwent surgical resection due to duodenal stricture. Contrary to common beliefs, histopathology examination revealed concurrent duodenal immunoglobulin G-4 related disease (IgG4-RD) and Brunner’s gland hamartoma (BGH).