argo said:A spell doesn't have to give a bonus/penalty to have the stacking rules apply:
<snip>
So if the target made one will save and failed one he would be frightened (the "best" effect applies) but if he made both saves he would only be shaken since identical spells don't stack.
Right.
Except when the effects are explicitly defined as cumulative:
Becoming Even More Fearful: Fear effects are cumulative. <snip>
It seems that this is a case in which there is a general rule (the one Wish stated perviously), overriden by a specific exception (the definition of Fear).