If you have a block and you run
you will end up with the same block id for the original block and that block in the clipboard.
Instead you can do this
$this->set( 'blockIdentifier', $this->getBlockObject()->getProxyBlock() ? $this->getBlockObject()->getProxyBlock()->getInstance()->getIdentifier() : $this->getIdentifier() );
Then in your view.php you can do
<div id="<?php echo $blockIdentifier ?>"></div>
and trust that all the blocks on your page will have unique ids, even if pasted from the clipboard.
Update: Shahroq has wisely informed me that this code only works in concrete5.6.0 and above. In versions below that it will throw an error as the the method
Block::getProxyBlock() did not yet exist.