@NitinCT , I believe what is happening has to do with how Marketing Channels and Tracking Codes work.
Marketing Channels are evaluated and applied when every hit is received by AA. On the other hand, Tracking Codes are set when AA first receives a hit with that code, and then remembers it for the visitor for up to the Tracking Code's expiry (default is a "Week").
Your segment based on Tracking Code includes those visitors who have ever been to your website via a tracking code. But also, some of those same visitors could have come to your website through other means, e.g. Referrals, Organic Search, etc.
So that's why you see Organic in your report (together with other Marketing Channels). That's also why AA discourages you from reporting Marketing Channels with Tracking Codes, because you're dealing with different expiries, which makes interpreting the results more challenging.