(I could be wrong but I think there actually were seven mitochondrial "Eve's". Anyone?)
There was only one, but she had several descendants who were the ancestors of various groups of mitochondrial-DNA sequences. Seven of them had lived in or near Europe; these are the "Seven Daughters of Eve", the title of a book on research into this subject.
Yes, seven,
but there were actually more women around at the time it is my understanding that "her" (I forget Bryan Sykes name) mtDNA is the one whose descendants survived to present day. A minor distinction, but....considering the need to reduce confusion.