You guys need to lighten up. This is a pure speculation thread that won't ever be answered. The shows over and even if it was continuing there would never be a true answer because unless they have an ending were they both die, in battle or of old age in each others arms, the question will never be answered.
two actually, one was killed by Doctor Leslie Thompkins who wanted to try and show Bruce the results of letting Children work with him
And the other was Robin in the Future during the Dark Knight Returns
Actually that was an alternate timeline and not part of the Batman continuity.
And they've retconned it so Black Mask killed Robin IV so they didn't have to deal with Leslie's bad characterisation. They made an action figure of him with the equipment he used to kill her, her bloods on it I think, as well.