How to avoid duplicate content in Blogger Blogs?

One can avoid having duplicate content in the blogger blogs by adding below script
Blogger Login>Layout>Edit HTML> Find </head> >Put the code below exactly above the code </head>
<link expr:href='data:blog.url' rel='canonical'/>
>Click Save Template

One knows that it is disastrous to have duplicate content on the blog as the same is taken as spam by these search engines.