Can i have a supplier as a customer also?

Hi office-southheat Thanks for reaching out to us here on the Community. It's not possible to create a customer with the same display name as a supplier. You can create a customer that has the same company name as a supplier and enter in the customer display name field something that identifies them as customer e.g. (Customer) at the end of their name. The company name will appear on the sales transactions and the display name only appears within the lists in your QuickBooks account.