Why RAC 1 is better
RAC 1 is first in the upgrade queue. When the very first confirmed passenger cancels or does not board, RAC 1 gets the full berth. RAC 2 gets it when the second slot opens.
Probability comparison
RAC 1: ~95% chance of getting a full berth (before or during journey). RAC 2: ~85-92% chance. Both are excellent positions — the difference is mainly about timing of when you get upgraded.
Both guarantee travel
Regardless of whether RAC 1 or RAC 2 gets upgraded to a full berth, both passengers travel on a shared side-lower berth if no upgrade happens. Neither is denied boarding.
What to do with RAC 1 or RAC 2
No action required — you will travel. Set a WhatsApp alert on PNR Alert to know the moment your RAC upgrades to CNF, so you can plan your journey accordingly.