I am trying to track click of an articles.
I kinda found answer to this. So, GA sessions are sessions, which means if some user visits any site multiple times still it will be counted once only. But url shortner works on clicks, once you click on any url its counted. So there can be 10 or even 20 clicks under single session.
Closest solution I can find this this issue is to setup a cookie & not to record user's click if he is visiting again in certain time frame. I am still testing this functionality but looks like its working decently.