OK, it’s an error in the php logic. In your code you are saying IF chapo, display ‘chapo’ and also the_content(). You need to use ELSE to display one or another, such as:
<?php $field = get_field('chapo');?>
<?php if( !empty($field) ) { ?>
<?php echo $field; ?>
<?php } else { ?>
<?php the_content(); ?>
<?php } ?>
I am also adding a condition that says: if ‘chapo’ is not empty. Which is helpful most of the time.
Cheers!