Photon Unreliable Observe Option

Does the photon unreliable observe option check only run the most recent packet received? Or would it play up older packages that of some reason got delayed as well? Wondering if I would need to use a packetID myself to check against.

The unreliable observe option does not repeat any messages. It constantly sends new ones to replace outdated ones. You use this when you need the latest info only.
No need for packetIDs in any case.