@ Nanji,
As Ash explained, sometimes you get a second AOR when you send full documents... BUT, sometimes you only get the first AOR and you keep that number until the end of the process.
Let me explain, it depends on the officer that manages your case, he has 2 options when he receives full documents:
Receive the documents and create a new file number (that will be attached to the previous AOR) OR use the first AOR until the end. Both of the numbers start with a B.
It does not make any difference if you receive 1 or 2 numbers. Congratulations on receiving your medical orders!!!
In regards to your questions:
Usually, when youy get 2 numbers, you can check your e-CAS with either number. They will show the same result, since thay are both related to your case.
In your case, you only received the first number... and that is perfect (just a different aproach)... I would worry about it.
NeN