Why need 2 forms, and your form1 has no submit button, when you submit, only form2 got submitted, try this:
<form action="index.php" name="form1" method="post">
<input type="text" name="contact_name" value="Carl">
<input type="text" name="contact_last_name" value="Mora">
<input type="submit" name="checkdetails" value="Check">
</form>