I don't know if anyone else does this, but I know at least a few people do, myself included. See if this fits you--
When I pronounce Black Adam, I say "blak ah-dum".
However, when I say Teth-Adam, I pronounce it "teth-ah-dahm".
They're both Adam, the same word, spelled the same way... why does the Teth make it so much more exotic? Is that the way it should be said? Or should it always use exotic pronunciation? Should it be "blak ah-dahm"? Or "teth-ah-dum"? Because both of those would be weird.