remove duplicate declaration

interfaces/change/change.go

@@ -26,10 +26,3 @@ type Payload struct {
 	Original ygot.GoStruct
 	Modified ygot.GoStruct
 }
-
-// Payload contains two ygot.GoStructs, the first represents the original state
-// before the change was applied and the second repesents the modified state.
-type Payload struct {
-	Original ygot.GoStruct
-	Modified ygot.GoStruct
-}