Yes Entity Names must be unique, even across Entity Types. For example, you cannot have a Customer called 123 and a Table called 123. Using Phone is the best way, it’s also the necessary way when using integrations with Gloriafood etc.
Please note I have edited your posts to remove customer phone numbers and also removed your CSV uploads (those containing customer data). Please be aware this is a public forum and we must respect the privacy with third party customer data.