Thats done in the /skin1/main/order_info.tpl file, and you are absolutely right about showing that info, not because it looks silly, its because it is using the direct username for the provider which gives a hint to a possible hacker.
Just take these lines out:
Code:
<tr>
<td valign="top">{$lng.lbl_provider}</td>
<td valign="top">{$products[prod_num].provider}</td>
</tr>