@daksh1227,
Don't have sex without protection if you don't want a pregnancy to result.
Precum has very little to no sperm in it BUT that does not mean that withdrawal is a terribly safe method of sex or birth control as, if the withdrawal occurs when male orgasm is starting, then there can be some sperm. Plus (I am assuming this is a gang bang situation) if the woman already has sperm in there from someone else, there might be a danger to the man. And even with just precum there is a danger of passing other STDs.
If there are two lovers, it's tough to tell which one will cause a pregnancy. That's what DNA testing is for. But it is possible for either lover to be the father, and having an earlier lover in the same session is hardly protection against anything.