Hello!
Well - you can add the ID field (internal system user ID) to a Print Template. That would give you a "serial number" for Print outs.
Note that it will not show in the "Create Multi Result" page, but you will have to select the "Print" and select the new Print Template.
Customization > Print Templates
Duplicate the Account List template, and edit the new one.
Add the following code to the appropriate section of the html.
<tr>
<th class="nwaLeft">SerialNo</th>
<td class="nwaBody">{$result.id|escape}</td>
</tr>
So the key there is the {$result.id|escape} that gives you the said value.