Question on Celestine, Geminae and wounds

I recently had a battle using Celestine and her Geminae. Only one was standing at the time that Celestine failed two saves against melta gun shots. The rules state that 'whilst at least one Geminae Superia is still alive, resolve any wounds suffered by Celestine against the Geminea Superia closest to her instead.' Melta gun shots are instant death. The question came up, should the Geminae take both melta gun shots, or just the first because it would instakill her. The shots are considered simultaneous in the rules.

Since it was just a friendly game, after about 10 minutes of trying to figure it out, we just rolled a d6 for it, resulting in the Geminae taking both shots, but I just feel that maybe Celestine should have taken one of them.

Unfortunately, I can see it going either way, and, because the way it rolled was to my advantage, I decided to see what people here thought.

Did we get it right, or should Celestine have been wounded by the second shot?

The wounds would be transfered to the Geminae but as they caused instant death on her she would have to roll the saves separately, and if she failed the first the second would be re-allocate to Celestine

As Djbz said, also keep in mind that this is not a look out sir (Celestine -> Gemenae) and The Gemenae are characters. Thus you the wounds get automatically allocated to the Twins, and they themselves could then look out sir them to other members of your unit. Very hard to take down.