Crafting already does what you're trying to do. And recipes aren't stored in a string, that's an array OF strings.
The member_array check in eventLearnRecipe prevents multiple recipes from being learned (multiple redundant ones, that is)--which suggests to me your character was the victim of some bug (for instance, a call eilonwy->AddRecipe(thing) would have skipped the check--that would be the fault of a bad call, not a bug in crafting.)

If some other, in game possible reason would have caused her to learn multiple recipes for the same thing, try to find out what it was / let me know, and we'll fix it.

-Mahkefel
