If you have the same customer and supplier data you do not need to make the contact data with the customer and supplier. you also can set default type of new contact added so next time you add new contact you not need to change it manually again.
I. Contact
Step 1. Select and Edit Customer Data
Step 2. Select Information then change Type to SupplierCust to assign the contact as customer and supplier too
Step 3. Then you can check the customer you have been set its already appear in supplier list too
II. Setup
Step 1. Select Module Configuration in "More Menu"
Step 2. Select Contact then Set Default type of new contact added
