Common: Apply distinct to sql placeholders

Modules.Patterns/Pattern.vb

@@ -10,4 +10,12 @@
     Public Overrides Function ToString() As String
         Return $"{{#{Type}#{Value}}}"
     End Function
+
+    Public Overrides Function GetHashCode() As Integer
+        Return (Value.GetHashCode & Type.GetHashCode).GetHashCode
+    End Function
+
+    Public Overrides Function Equals(obj As Object) As Boolean
+        Return Me.GetHashCode = DirectCast(obj, Pattern).GetHashCode
+    End Function
 End Class