You may use same set of recomm letters but you can not use the same petition letter obviously. You need to prepare a different petition letter specifically used for EB1a application.
Just for reference.
• 回複:回複:請問有沒有申請NIW和Eb1a用一套完全相同的推薦信,而兩種都批了? -WorthIt- ♂ (33 bytes) () 06/13/2008 postreply 14:06:45