I used Immigration Paper to go back to canada last year to pick up the maple card. My passport never got stamped from Canadian side, stamped once on US side.
I think you need to be careful about the stamps on your passport, need to find a way to explain it. 
It's not a big deal if you get caught. I heared they just ask you to re-count from that day on.
回複:Your passport
所有跟帖:
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                    回複:回複:Your passport
                     -xiejoe- 
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                        09/15/2004 postreply
                                                13:15:15