Just a thought about all this..........
James Graham is born 1841 and his parents William and Margaret (Addie) both die. He is adopted by his uncle James and Christina Graham (Cummings). As he is adopted he signs James Graham's death cert in 1868 as his adopted son, and by this time has his own son named William (called after his natural father) who then signs James's death cert in 1909 unaware of his fathers natural parents William & Margaret.
Seems possible but hey that's geneology for you.