回複：AP回國I-94卡是否要上交？

I went home with AP in October 2004, handed in both copies of my I94 (one for F-1 when I came in 2000, the other for H1-B after I graduated in 2003), I came back on Nov 03,2004 and got a new I-94 form.

So my experience is: yse, you should hand in your I-94 forms.