This is pure speculation...but I think Evony has 2 different (or more) sets of drop rates for Age II due to the merged accounts from Age I.

The game plays very differently when starting fresh or tranfering an already built account.

Also for a while they claimed was a bug they fixed that gave higher drops.

I saw a clear change on my server all in one day...the rates changed dramatically. One instant I was bragging how I could farm for mich scripts..the next day and never since have I ever gotten a mich script.....

I believe that is because if they give mich scripts enough for new accounts the older accounts get too many.