DB Design :: How To Select NULL Values In A View

I am creating a view and want to select records where the value of a Customer field (Klant Test Plan) is NULL or has exact the same value as for example customer field 2 (Klant Schedule).

I have already the code below:

SELECT DISTINCT
                      TOP (100) PERCENT dbo.Product.ERPKey, dbo.TestPlan.CoA, dbo.TestMethod.WorkInstruction, dbo.Customer.Name AS [Klant Testplan],
                      Customer_1.Name AS [Klant Schedule], LEFT(dbo.ShopFloor.ShopFloorNumber, 7) AS Schedule,
                      CASE WHEN Customer_1.Name = 'ItsMe BV' THEN Customer.Name ELSE Customer_1.Name END AS Customer
FROM         dbo.Customer AS Customer_1 INNER JOIN

[Code] ....