yep, there were two systems, Bosch and Sagem supplied the whole distributors, VW put in whatever was on the shelf on the day.
If the old one says Sagem you need to buy one for that system.
Beru for example sell for both systems, which have different rotors and caps.
You can change the whole distributor but since you need to then align with diagnostics PC I would only do that if the hall sender is fecked, plus whole dizzy = £££.