---------------- 
My Code :
---------------- 

$aSeq_Number = "1,2,3,4,5";
$aOverview = imap_fetch_overview($link, $aSeq_Number, 0) 
if ( is_array($aOverview) ) {
  reset($aOverview);
  while ( list($key, $val) = each($aOverview)) {
    echo "$val->from<br>";
  }
}

The message no of my mailbox is three.
The first sender is yakang@orgio.net, the second senderyeon@samsung.co.kr, the third sender jph@orgio.net

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The result :
----------------
yakang@orgio.net
yakang@orgio.netyeonsh@samsung.co.kr
yakang@orgio.netyeonsh@samsung.co.krjph@orgio.net

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I think that $from value is appended.