I noticed that we create a multitude of customers as each visit, especially in groups of 3, it seems that the management of cookies does not work very well.
This would not be a big problem by activating the automatic deletion plug-in, but by creating "valid" customer the ID numerator has notable increases.
Could not you make a separate table for temporary customers?
Which nopCommerce version are you using? Did you customize the solution?
Out of box it creates only one customer and a cookie is sent to the browser to keep track of the user. So unless the browser is not handling the cookies correctly or you have made some customization, it should not create more than one guest customer.