Do you intend to merge duplicate records with this page? If yes, then you can leverage Matching Rules and Duplicate Rules provided by Salesforce. These are out of box features which are readily available for use.
Moreover, every Salesforce instance comes with preconfigured rules for Accounts, Contacts and Leads which only need to be activated and used.
Hence, you don't really need to build a custom Visualforce page to accomplish this unless there is a specific custom behaviour that you intend to achieve.
Do you intend to merge duplicate records with this page? If yes, then you can leverage Matching Rules and Duplicate Rules provided by Salesforce. These are out of box features which are readily available for use.
Moreover, every Salesforce instance comes with preconfigured rules for Accounts, Contacts and Leads which only need to be activated and used.
Hence, you don't really need to build a custom Visualforce page to accomplish this unless there is a specific custom behaviour that you intend to achieve.