Do Oventrop press fittings and pipes have to be from the same brand?

Hello, dear people, I still have some meters of Oventrop multilayer composite pipe Copipe 16 x 2.0 stored in the basement. Unfortunately, there are hardly any Oventrop press fittings left. An acquaintance told me that for the Oventrop composite pipes you are only allowed to use Oventrop fittings. Is that really the case, does anyone have experience in this area. Best regards Georg