 Consequentialists who hold that killings of innocents are intrinsically bad can avoid this prediction. As long as a murder is at least twice as bad as an ordinary death not by murder, consequentialists can explain why you ought not to murder, even in order to prevent two deaths. So there is no in-principle problem for consequentialism posed by this sort of example; whether it is an issue for a given consequentialist depends on her axiology: on what she thinks is intrinsically bad, and how bad she thinks it is.