Vista - How to fix A DataTable named 'Tag2' already belongs to this DataSet.(XML/Datatable)

Hi!
Have a dataset that I need to populate with 4 datatables. The name of
the datatables needs to be Tag2. This is because I need to return the
data as xml in this specific format (dataset.getxml()) :

<Tag1>
<Tag2>
<Tag3>
<Attribute1>2003.09</Attribute1>
</Tag3>
</Tag2>
<Tag2>
<Tag3>
<Attribute1>2354.62</Attribute1>
</Tag3>
</Tag2>
</Tag1>

So my problem is, when I add the second table named Tag2 I get "A
DataTable named 'Tag2' already belongs to this DataSet" errormsg.
How can I avoid this?