Hello,
Yes for older Versions an adaption of the PLCprogram (upgrade to newer Version) is nessesary. Thats why the Ordernumber has been changed.
An identical Ordernumber means nothing to do for change. An -x change (-1 → -3) means that you have to check the scenario and there is a possibility for change requirements.
I have heard that for some of the modules there are still improvments planed to reduce the incompatibilities via firmware adaption in the future.
To be sure what old, new Versions means in this context. You have to ask the local Support.
Greetings
Michael