p252,
Generally, TSC does not mail duplicate copies of I-485 receipt notices. They will give you your receipt number for future reference. You can use that receipt number to obtain any interim benefits like EAD, AP etc. Their logic is that mailing you a duplicate receipt notice is not critical to the processing of your case. My wife and I filed our 485s together back in 2001. While I received my receipt notice my wife's was lost in the mail and till today we do not have her receipt notice (nor did we need it.) She had absolutely no problems getting any interim benefits. We did have to include an explanatory letter containing the receipt number given to us by TSC in any applications that we filed for her.