I am very proud to announce that I have found a bug with Gmail. Yes ... a bug.
When two different people send an email to only you and the subject line is exactly the same, GMail treats it as same conversation and clubs them together.
This document on GMail Help says that "Gmail groups all replies with their original message, creating a conversation."
I think a conversatin is only identifiable with the recepiants and the subject line. The subject line can have standard modifications (such as Re:, FW: etc.) which are ignored by GMail when creating conversations. So if two entirely different people send in their mails to same group of recepiants with the same subject line, GMail would treat it as same conversation and club the two. The email contents could be different. In effect the entire point behind having a conversation is lost. We are not clubbing related information but clubbing unrelated information !
Time for some fixes... !