Im using a spell book with two abilities, but when i try to use the first ability the unit casts the second.
The abilities are copies of eachother with some changes made.
That is not a spell book bug, that is a normal bug. You have to base the abilities on two different abilities, else the orders will be screwed up. Best solution is to delete one of your copy abilities and re-create it, basing it on something else that is similiar :).
hmmm but what if i wanted a spell-book filled with spells working like that one? i mean some spells are uniqe in their functions and finding replacements might not always work.