Error: Column already has a DEFAULT bound to it. Could not create constraint.
Description: The constraint trying to create for the column is already exists.
Solution: From system table sys.objects find out the constraint, rename or drop the existing constraint and then create the new one.
SELECT name ,OBJECT_NAME(parent_object_id) AS ParentTable ,OBJECT_NAME(object_id) AS ConstraintName FROM sys.objects WHERE type_desc LIKE '%CONSTRAINT' order by name