Bharath,
In Mendix, each microflow is treated as a single database transaction. So if the microflow initiated by User One has not completed, any objects created in that microflow won't be available to other users. I believe that is the problem you are encountering.
To work around this, you could have the microflow initiated by User One complete. At the end of that microflow open a small notification page with a Microflow Timer widget on it. The Microflow Timer widget could call a microflow that pauses for the period of time you want to pause (or checks for an updated of an object created in the first microflow before proceeding). Then you could close the page with this microflow and proceed.
Alternatively, the Pusher widget from the appstore (https://appstore.home.mendix.com/link/app/107957/) may be useful for what you are trying to accomplish.
Hope that helps,
Mike