回複：回複：you can't have two niw at same time

My opinion is ok if you want to file a second petition even if in the same category since the law does not define such issue.

You have to mention your current petition including current I-140/I-485 receipts in your second petition. When you fill your new I-140 form, you are required to answer such question on a separate sheet though you do not have to includ the receipt, just include the case number. Take a look at the 140 form again, you will find it.

Good luck.