If another person is chiming in they are the second person. The observer is the first person and the second is the one chiming in.
In our area sometimes we know the species, but as we are using iNat to further the research and properly ID species in the area even a single confirmation/agreement/disagreement is highly valuable.
In many cases, especially with plants and insects we don’t know at all what they are, often not even to family level, let alone genus level, and it’s rare we get anyone who adds any further info of any sort.
I’m opposed to keeping the casual grade even after others have posted an agreement/consensus. That will, I think, have detrimental effects to participation.
Maybe a tiered system?
Casual - single ID
Confirmed - two IDs
Research Grade - three IDs
One of the problems is that in many areas, especially with poorly known species and areas any changes to the current system will wreak havoc on current information.