Sometimes after conception, another ovum from mother gets fertilized; hence there are two babies of multiple babies; but they are not twins.
Medical language calls it “Superfetation”.
When two or more ovums are fertilized at the same time, they are called twins; but not identical twins.
When one fertilized ovum divides to two, which does not occur as a routine; two identical babies are born; either male or female. As they share the same genes look identical, called identical twins.
Identical twins can share good or bad health.
I got pregnant while I was already pregnant! Woman gives birth to two babies on the same day but they are NOT twins
As one of only 11 women ever reported to get pregnant while already pregnant, Mrs Grovenburg‘s pregnancy was eventually identified as ‘superfetation’, meaning two babies are conceived at different times, born on the same day yet – medically speaking – are not considered twins.