My researches from lawyer’s site and different forums showed that most people recommend re-link. They think that two I-485 will cause your case delay or trigger interview. So I wanted to give relink a try.
I have tried to relink The EB1a was current on July 2006. The trend of NIW cut-off movement is very quick. I closely followed this thread during the time: http://boards.immigration.com/showthread.php?t=205051&highlight=485+relink
Then the DOS prediction came out that the EB2 will retrogress during summer of 2007 and the filing fee will increase by USCIS. At the same time, there was some good news from persons who filed two I-485. Xiaobaitu confirmed that two I-485 was workable.
I made my mind to file second I-485 when I concluded that there is no punishment or negative effect to either I-485 application. The official document about this issue is the USCIS standard operating procedure(even though it is outdated). http://www.ilw.com/seminars/august2002_citation2b.pdf
The page 4 of it is about “Second filing”. “second filing refer to I-485 applications submitted to a service center with a new filing fee even though on may be pending at another INS office. Second filing will be handled under the normal process.”
Hope this will be helpful to you.