I really think something is broken with epic scroll drop mechanics. I know it is hard to show as you need to kill thousands of mobs to show something isnt random, but something seems off. I have farmed von5 a lot and usually get no scrolls, sometimes get 1 and rarely get 2 in one run. The times I did get 2 scrolls in one run both times it was 2 stonemeld plate scrolls. That cant be a coincidence.
Two scrolls dropping in 1 quest doesnt happen very often. I have noticed the same scroll sometimes drops twice in one run for different people.