You're certain the last one is 100% drop? if so, I'd take that over 50%
EDIT: You're right. It's guaranteed. Ran it 5 times and got 5 copies. Funny enough not a single one of those reduced her cost. really pissed me off lol.
EDIT 2: I've fed her about 15 copies and got only 2 CRs. This is down-right retarded.