How can I compare two sentences the entered in Input text only for alphabet that contains numbers / symbol/ spaces for Duplication?? 

Example :
lets say a user enter a title name in Input text and stored in the website like this :

> 
> Hello World
> 
> 
> 

and another user want to enter and submit a title name in the website Like this:

> 
> Hello,World
> 
> 
> 

Or

> 
> Hello World,\*(':?
> 
> 
> 

What i want to get is to check this string is duplicated or not ? excluding all numbers and symbols?

I have tried this formula , but i didn't get what I want ? 

```
$title = preg_replace('/([^a-zA-Z0-9]+)/i', '', $title );

```