It cud be possible that two ppl receive the AOR at the same time(AOR by definition is acknowledgement of receipt.They just verify that the forms are filled in correctly and acknowlede that they received ur application).Once the initial assessment is started they ask for more docs.It cud be possible that person A sent all reqd docs per checklist and person B did not.During assessment lets say person B was missing IELTS to evaluate for language profeciency then they wud ask for IELTS results and keep the file on hold where as person A's file is complete, it cud be accessed properly and moves ahead.This is my perspective and it cud vary for number of reasons unknown to me.I also feel that it cud be upon the officers accessing the files, their efficiency on accessing the files or transferring of the files to locations which might take time to access the files.
Hope I did not confuse you further.
Regards,
AP
