You can't add it as a separate line, you would have to add it to the existing name... so instead of:
$nextIndex = count($WA_PP_ECO_Do_itemized[0]);
$WA_PP_ECO_Do_itemized[0][$nextIndex] = "Name" . strval($cartIndex+1) . "";
$WA_PP_ECO_Do_itemized[1][$nextIndex] = "".$drinkitz->DisplayInfo("Name") ."";
$nextIndex = count($WA_PP_ECO_Do_itemized[0]);
$WA_PP_ECO_Do_itemized[0][$nextIndex] = "Package" . strval($cartIndex+1) . "";
$WA_PP_ECO_Do_itemized[1][$nextIndex] = "".$drinkitz->DisplayInfo("Package") ."";
it would just be:
$nextIndex = count($WA_PP_ECO_Do_itemized[0]);
$WA_PP_ECO_Do_itemized[0][$nextIndex] = "Name" . strval($cartIndex+1) . "";
$WA_PP_ECO_Do_itemized[1][$nextIndex] = "".$drinkitz->DisplayInfo("Name") ." - ".$drinkitz->DisplayInfo("Package") ."";