Once the sperm reaches the egg & there's left over sperm still swimmin around. what happens to the other sperm

the rest of the sperm hover round the egg not being able to get in once the first one has so they just die. twins happen when the women releces two eggs not one i think and itentical twins is where the sperm gets in the egg and somehow the egg devices into two eggs stuck together growing separte babbies. thos is hard to explane and im not a expert but this is to the best of my womanly knolege.