Hi,
You had Old Release strategy 01 with old Release Code (01) , now you creates new Release strategy 02 which have new Release Code (02) and you do not want Old release strategy triggers for the PO.
Without changing any setting for old release strategy 01, you just keep all BLANK RELEASE VALUES in your old release strategy 01 with release group and release class in CL20N or CL24N and save.
You can test now with new PO creation and see how release stretegy 02 will be triggering!
Regards,
Biju K