Four front teeth fall out, two big ones grow back?

My friend’s great-grandma, or great-aunt, I can’t remember which at the moment, told her this little story.

Her son lost all four of his front baby teeth, but instead of four permanent teeth growing back, two big permanent teeth grew back!

Has anyone ever heard of this happening before? Is it common? I can’t for the life if me find any information on this!

I’ve seen it, the incisors are fused (syndontism) or are incompletely twinned from one root (schizodontism). Not at all common with permanent teeth. It is found more with deciduous teeth. Some info can be found here and here with pictures.

Thanks peri! I knew there had to be information on it somewhere, but I had no idea what the condition was called!