You get a cure along with a curse for being awesomely mischievous. They may cancel themselves out, but it still makes me feel better.
Actually, the feature allows you to change a cousin's karma
total by 1 number only within a 24 hour period, but the reason your second cast didn't generate an error is that the feature also allows you that same period of time to change how the total has been affected. (Repeating the same cast, however [two or more cures or curses within that same period] WILL bring up a message asking you to wait 24 hours.) So, whichever way you cast the karma initially was canceled out by your second (different) karma cast, and your last karma cast is what presently stands.
I'm not sure if an illustration of this has been provided before, so here goes: If karma is +10/-10 (total 0) to begin with, a cure will make it +11/-10 (a total of 1). A curse by the same caster given within 24 hours of the cure will correct it to +10/-11 (a total of -1). Following this up with another curse will generate an error, but following the curse with a cure will re-correct the total to 1. In light of this, if you wish, you still have until a full day after your first cast made today on that account to change the way you've affected her karma total.
Way to put you on the spot, eh?
Sorry for the interruption with mundane stuff