Two different actions don’t produce exactly the same utility, but even if they did it wouldn’t be any problem. To say that you may chose any one of two actions when it doesn’t matter which one you chose since they have the same value, isn’t to give “no guidance”. Consequentialists want to maximize the intrinsic value, and both these actions do just that.
Of course hedonistic utilitarianism doesn’t require completeness, which, by the way, isn’t one of its tenets either. But since it is complete, which of course is better than being incomplete, it’s normal for hedonistic utilitarianists to hold the metaethical view that a proper moral theory should answer all of the question: “Which actions ought to be performed?” What could be so good with answering it incompletely?
Nobody is calling “a universal decision theory a moral theory”. According to hedonistic utilitarianism, and indeed all consequentialism, all actions are morally significant.
‘Moral’ means regarding opinions of which actions ought to be performed.