I actually did this on mine. I liked the orange button, so I used the regular Customize area to put the information in the second button, emptied the first button, then modified index-home-callout.php (I did this in my child theme so future updates would not overwrite it):
replace the following in index-home-callout.php:
<div class="btn-area">
<a href="<?php echo esc_url($callout_setting['home_call_out_btn1_link']); ?>" <?php if( $callout_setting['home_call_out_btn1_link_target'] == 1 ) { echo "target='_blank'"; } ?> class="callout-btn1"><?php echo $callout_setting['home_call_out_btn1_text']; ?></a>
<a href="<?php echo esc_url($callout_setting['home_call_out_btn2_link']); ?>" <?php if( $callout_setting['home_call_out_btn2_link_target'] == 1 ) { echo "target='_blank'"; } ?> class="callout-btn2"><?php echo $callout_setting['home_call_out_btn2_text']; ?></a>
</div>
——WITH————
<div class="btn-area">
<?php if($callout_setting['home_call_out_btn1_link_target'] == 1) { ?>
<a href="<?php echo esc_url($callout_setting['home_call_out_btn1_link']); ?>" <?php if( $callout_setting['home_call_out_btn1_link_target'] == 1 ) { echo "target='_blank'"; } ?> class="callout-btn1"><?php echo $callout_setting['home_call_out_btn1_text']; ?></a>
<?php } ?>
<a href="<?php echo esc_url($callout_setting['home_call_out_btn2_link']); ?>" <?php if( $callout_setting['home_call_out_btn2_link_target'] == 1 ) { echo "target='_blank'"; } ?> class="callout-btn2"><?php echo $callout_setting['home_call_out_btn2_text']; ?></a>
</div>