Well my friend, I'm a declared and proud DD fan and for me it is very difficult to find something like DD stuff... But I dare to recommend you the next bands and albums...
-ULVER - Perdition City: It has some elements which reminds me DD stuff on Sacrilege or Dies Irae...
-AMON DUUL II - Phallus Dei: This a classic psychedelic kraut rock album from the 70s but it has some dark sections and some lyrical vocals...
-RUNAWAY TOTEM - Andromeda: Again, some lyrical vocals and dark (but be careful, repetitive) sections...
-ORDO EQUITUM SOLIS - Hecate: Same of Runaway Totem. Both are very interesting Italian bands...
That's what I remember right now. I insist that list is made with albums with some elements that I'm sure you enjoy on DD discography but not necessarly they're close to DD stuff... Anyway if I remember something else be sure that I will post here again...
Best regards...