Clean installation of OpenERP 7.0 from community backports, with eInvoicing module.

Create a second email template for customer invoice (cloning the existing one).

Create a customer invoice.

Validate the invoice and click the button to send it by email.

Any time you change the email template combobox, OE create a new record ir_attachment.

Is this the correct behaviour or Is this a bug?

PS: openerp.com demo act the same way (you can see that installing knowledge module)