We are showing the finish button on each quiz if only 1 page, but also showing the continue to next quiz button.

You should only show finish if the end of the quiz? 

Instead of:

<?php if($item->quiz_type != 0):?>

I would advise; 

<?php if($item->quiz_type != 0 && empty($item->chained_quiz)):?>

I've done it with a layout override anyhow, but the same would apply for the last question, you shouldn't see a continue button if it's the last question.