Why do you need if/else, when both are doing the same? Is this

elsif( (!$post{'page'}) && (!$self->session->param('page')) ) {
  $self->session->param('page' => 1);
} else {
  $self->session->param('page' => 1);
}
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not the same as

else{
   $self->session->param('page' => 1);
}
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?

And

if($post{'page'}){
  ...    
} elsif( (!$post{'page'}) && ...) {
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also looks redundant.

How about this:

my $session = $self->session;
foreach (qw[ page ] ) {
   $session->param( $_ => $post{$_} ? $post{$_} : 1);
}
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This also scales nicely with an increasing number of session variables (if all of them default to 1 ).