Yes, I noticed your use of a comma, and even questioned it myself, though PHP.net's manual page on [man]mail/man uses a comma in their example, so it doesn't seem as though that would be wrong 😉
I'm equally stumped. You didn't answer my other question though; you had set a From: address as an additional header. Is this working? On the e-mail you receive, does the From: line indicate such?
Also; try to run a normal mail() command using the Bcc: address you're trying as the To: address. Just send a short, simple test message, subject test, etc. MAYBE the remote server is blocking the mail, or the mail server is refusing to send it, etc. etc. Who knows.
EDIT: I uploaded the code you first posted to one of my remote Unix servers... it worked fine. I got the e-mail in the 2 from mailboxes, and also in the Bcc: address (as a Bcc message). All addresses were separate mailboxes. My guess is that your mailserver does not support Bcc, it is disabled, etc. etc.
Use [man]phpinfo/man and tell me how your server is configured to send mail (should be in the first block of information).