It's the letter you called the 221(g) 'slip' ... since you already sent the original, include a copy.
As for 2 passports, it depends on who the e-mail was addressed to.
If you continue to be confused ... you should be talking to the company's immigration lawyer ... not a group of strangers on an internet blog, nor non-attorneys in HR.
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I agree with Attorney Capriotti.
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