Hello Muhammad
In such a scenario, when R2 and R3 “see” each other’s multicast traffic on the 192.168.234.0/24 network segment, a negotiation between those two routers takes place. This is part of the PIM assert mechanism. They exchange information, including their own locally significant administrative distance to the source of the multicast stream as it appears in the local routing table of each router.
If this is the same, they then compare their IP addresses.
I hope this has been helpful!
Laz