As Your Question Here is The Answer....
Route of discuss tab :-
Random Question Unique id :-
The Title Of That Discuss Tab :-
ALL TOGETHER :-
Hope You know now...
After the discuss/
There is an unique Id given to that Discuss if any one's title is also same it will be also unique
You go to that link and see that how it is unique...
Just because of the random generated number and the title