Possible to join 2 lists at once?

Hello, I have a subscribe form on my site and want to be able to join 2 lists when they subscribe, is that possible? Basically I want them to join list 1 and 8. Here is my form:

<div class="foot1">
<h3 style="font-size:20px;">Join Mailing List For Special <br>Offers and Updates!</h3>
<form action=
"https://mysite.com/lists/?p=subscribe&amp;id=1" method=
"post" name="subscribeform" id="subscribeform"><br />
  <input id="email" name="email" required="required" size="40"
  type="text" placeholder="Email Address" /><input name="htmlemail"
  type="hidden" value="1" /><br />
  <input name="list[1]" type="hidden" value="signup" /><input name=
  "listname[1]" type="hidden" value="General Mailing List" /></p>
<div style="display: none;">
    <input name="VerificationCodeX" size="20" type="text" value=
    "" />
<p><input name="subscribe" type="submit" value=
  "Subscribe" /><br />