"Cain and Abel" from House of Secrets vol.1 #92 (DC, 1971) by Bernie Wrightson
From the issue that gave us the first appearance of the pre-Alec Holland Swamp Thing. Not a very splashy story, but the opening page by Bernie Wrightson is a great pic featuring both brothers in their respective houses' shared (and bustling) cemetery, with the House of Secrets and its "sad face" in the background. So what interests you more? Mysteries or secrets?