Yes that’s all true. Triploidy is where ALL 23 chromosomes are tripled because 2 sperm have fertilised one egg or egg has duplicated chromosomes before fertilisation. That’s what happened in my pregnancy. Baby doesn’t look like an alien. Looked surprisingly normal on 12 week scan. All organs there, heart beating healthily, head looked normal, arms, legs, fingers, toes. But as you say it’s not compatible with life. Triploidy babies have lived a few hours after birth at best.