You can set theme in your config.xml module something like:

<global>
    ...
        <template>
            <email>
                <form_email_email_template translate="label" module="form">
                    <label>contact form</label>
                    <file>contact1.html</file><!--the name of email template,  PATH = app/locale/code_ISO/template/email/contact1.html-->
                    <type>text</type>
                </form_email_email_template>
            </email>
        </template>
    ...
</global>

You can set theme in your config.xml module something like:

<global>
    ...
        <template>
            <email>
                <form_email_email_template translate="label" module="form">
                    <label>contact form</label>
                    <file>contact1.html</file><!--the name of email template,  PATH = app/locale/code_ISO/template/email/contact1.html-->
                    <type>text</type>
                </form_email_email_template>
            </email>
        </template>
    ...
</global>

EDIT:

If you haven't a module to do that and you want to create another contact form to send it for anther mail address, and maybe you want to customise it on adding the additional fields, you have to follow this inchoo tuto