Hidden Blade

If both instances of a repeated Hidden Blade (using Repeat given by for instance Temporal Portal) are targeting the same unit, you draw two cards total. As the card resolves, the repeated effect does not have a legal target, so no additional effect occurs.

Q: If a unit would be killed by Hidden Blade, but one of these cards replaces that unit’s death, does the unit’s controller still draw 2?

Yes. Hidden Blade attempts to kill a unit, then says that “its controller” draws 2. Even if the unit doesn’t die, it’s still on the board and information about its controller is still available, so that player draws 2. This is different from Baited Hook, which requests information about “the killed unit,” and can’t find any information if no unit was actually killed.