Product names on Sales Order grid?

Is it possible to display product names on the sales order grid? Magento is throwing an error `id "1128" already exist"` 

I think it's due to the fact that orders have multiple products. 

This is what I have:

```
<add>
    <header>Product Name</header>
    <join table="sales/order_item" condition="main_table.entity_id={{table}}.order_id" field="name"/>
</add>
```
