Request.Form will not force to ovrewrite the session.

Have you identified where the session data is overwritted in your code?

If yes, post that code so that somebody can suggest a solution.

Actually we are providing session for requestID. Based on requestID we can fetch data for particular request. Somehow it has copied data of one request from one user to the request of differant user.

We didn't get any code error for sure so we came to the conclusion that after displaying one request 'A' when we click on save it would have been taken different requestID 'B' (if session overwriting happens) and fetch data of that requestid and saved for requestID 'A'.
We are not sure session overwriting happens or not?

One more possibility there, while clicking on 'Save' button, there 'Request.Form' has been used to store new values and it replace new values with old values for updation.

collReqVariables = Request.Form

collReqVariables is NameValueCollection.

Does it causing problem? Does request.form is taking other user's data for update existing request?

Code is little tricky and dependent on other files so not useful to post.

Thanks.