<?php echo $content->category1?>
<?php echo $content->category2?>

그리고 카테고리를 탭 형식으로 보여주는건 아래 코드를 참고해서 적절히 수정하시면 될 듯합니다.

<div class="kboard-category">
    <?php if($board->initCategory1()):?>
        <ul class="kboard-category-list">
            <li<?php if(!$_GET['category1']):?> class="kboard-category-selected"<?php endif?>><a href="<?php echo $url->set('category1', '')->set('pageid', '1')->set('target', '')->set('keyword', '')->set('mod', 'list')->tostring()?>"><?php echo __('All', 'kboard')?></a></li>
            <?php while($board->hasNextCategory()):?>
            <li<?php if($_GET['category1'] == $board->currentCategory()):?> class="kboard-category-selected"<?php endif?>><a href="<?php echo $url->set('category1', $board->currentCategory())->set('pageid', '1')->set('target', '')->set('keyword', '')->set('mod', 'list')->toString()?>"><?php echo $board->currentCategory()?></a></li>
            <?php endwhile?>
        </ul>
    <?php endif?>
    
    <?php if($board->initCategory2()):?>
        <ul class="kboard-category-list">
            <li<?php if(!$_GET['category2']):?> class="kboard-category-selected"<?php endif?>><a href="<?php echo $url->set('category2', '')->set('pageid', '1')->set('target', '')->set('keyword', '')->set('mod', 'list')->tostring()?>"><?php echo __('All', 'kboard')?></a></li>
            <?php while($board->hasNextCategory()):?>
            <li<?php if($_GET['category2'] == $board->currentCategory()):?> class="kboard-category-selected"<?php endif?>><a href="<?php echo $url->set('category2', $board->currentCategory())->set('pageid', '1')->set('target', '')->set('keyword', '')->set('mod', 'list')->toString()?>"><?php echo $board->currentCategory()?></a></li>
            <?php endwhile?>
        </ul>
    <?php endif?>
</div>