Question about identicals and IVF

So long story short, we naturally conceived identical twin girls years ago and lost them due to TTTS at 20 weeks. We later went on to have our son ❤️ Somewhere in the last four years my honeys sperm got lazy so we had to do IVF for our “second”. We opted to transfer one embryo for my fear of multiples again but were told the egg may split anyways because of IVF and my history...

Is there anyone out there who has had this happen? Or can provide me a percentage? I’m kind of nervous since I always fall into that “it’ll happen to you” group 🤦🏻‍♀️