Customer failed to post... BadRequest

Customer CUSTOMER NAME
Customer failed to post to QuickBooks
BadRequest Validation Exception was thrown. Details:The name supplied already exists. :another customer, vendor or employee is already using this name. Please use a different name. The name supplied already exists. Another customer, vendor or employee is already using this name. Please use a different name. (Adding Item)

This alert means the customer record has the same name as an existing Customer, Vendor, or Employee.

Change the name of the customer and Retry this to resolve it.