Random thought I don’t think has specifically occurred to me before, and not sure I’ve read it here. I might as well post it in the “great aim to post something not already posted”.
There is the, perhaps rare possibility, that they could could have two different CODs, depending how everything actually went down at the very end. Up to this point, I naturally thought, “I wonder if they (collectively) were shot, or strangled, or this or that other COD.
Point is, maybe they have different CODs (or not). Maybe unlikely, but who knows.
To be more specific, maybe the above is possible if he wanted to get one victim out of the way more quickly, and spend more time with the other, ugh I hate to type that.

Maybe one victim was immediately/quickly shot, and the other killed in a more hands on way, strangulation/ligature, BFT, drowning, stabbing.