回複：do you have a check list?

I used the same supporting materials for the two I-140 petitions, even the recommendation letters were exactly the same - I asked my refrees to simply provide me the letters in duplicate, each with original signature.

Of course you need to write different cover letters for the two petitions, focusing on the key points in accordance with USCIS' requirements for different categories. This means you should treat the same materials in different ways for the two cases.

The only one document required for NIW petition but not for EB1a is the Form ETA-750B (IN DUPLICATE).

Good luck!