how to add xdodelivery.cfg with multi smtp_mail default="true" entries?

edit the xdodelivery.cfg with following content,

there are two entries "smtp_email" && "default="true"

but only the last(2nd) entry work well.

How to setup both entry work well?

--------------------xdodellivery.cfg------------------------------------

<server name="localhost" type="smtp_email" default="true">
<host>mail.abc.cn</host>
<port>25</port>
<username>erpnotice@abc.cn</username> 
<password>Abcd1234</password> 
</server>
<server name="localhost2" type="smtp_email" default="true">
<host>mail.abc.cn</host>
<port>25</port>
<username>raytest@abc.cn</username> 
<password>ABC.123</password> 
</server>

...

---------------------------------------------------------

Regards

Gavin.