Tamil Nadu State Transport Corporation [TNSTC] — Different ticket fares collected for same stopping in same bus by different conductors

It's almost a month that I am boarding the bus from the Virudhunagar police station stop and almost same bus. My bus ticket fare was around Rs.20/-.But I noticed that one of the conductor is collecting Rs.30/-from me for the same Destination quoting that he has to close the stage or else board the bus from the next stop. I want to know the correct bus fare for the stop I am boarding from .