I think XBT is right because she worked or is working in this field for a pretty long time. and also your receipt of 485 may come in very soon
I know that there are two opinions about this issue, i think you HAVE TO tell CIS by yourself at the moment of the second filing. I do not think you should really worry the system will automatically create the second A# for you case because the data is entered by A HUMAN BEING, so just making your situation clear enough will be fine.
good luck, this is only my personal opinion,
我瞎講您瞎聽。