I can’t imagine Hamas did this on purpose, they have nothing to gain and a lot to lose.
They have some macabre, satanic-looking ceremony to hand over black coffins, with the victim's images in front of Netanhayu as a vampire, loud Arabic pop music and an audience of thousands cheering, and you think they'd worry about the optics if the wrong body?
No, this was done to cause more pain. They long identified the Bibas family as a psychological tender point for the Israeli nation, and they're getting as much mileage as they possibly can from maximum cruelty.
And if the reaction is that the ceasefire fails, that's not a loss for Hamas. That's more footage to put on social media. They don't care about civilian deaths, the more the merrier as far as they're concerned, great for propaganda purposes.