Twins measuring 2.5 weeks apart

Jorden

Last week baby A was measuring 7w6d and baby B was just a gestational sac and a yolk sac. This week baby A is 8w6d and baby B showed up and is measuring 6w1d. Dr told us superfetation is VERY VERY rare and this likely isn’t what happened but there is a tiny chance it did. Likely it’s a vanishing twin, but I can’t give up hope until our next scan when we will know for sure what’s going on. Anyone else with a vanishing twin?