Twins and miscarriage

Sorry if this may be touchy to some. My friend had a miscarriage around the beginning of December and fell pregnant shortly after. She just found out she is having twins. She told me her OB said that she more than likely hyperovulated because her hormones were out of wack and that is what caused it. Well, I started to research online were hundreds of other women stated they fell pregnant with twins shortly after having a miscarriage also.  I know that identical twins is another story but i found it pretty fascinating. Any other ladies have similar stories? I have another friend who announced she was pregnant very early on only to have a miscarriage and then surprisingly a few moths later she posted on Facebook she was pregnant with identical twins. Thought it was pretty neat!