how does the confusion over junior's name demonstrate his change in culture

“My name is Junior,” I said. “And my name is Arnold. It’s Junior and Arnold. I’m
both.” I felt like two different people inside of one body.’ 

Junior's two names (Junior and Arnold) symbolise the two different cultures he lives in and exemplifies their differences. You might also mention the fact that Junior is referred to as 'apple' by some of the people on the reservation. This isn't a positive word, as the name translates 'traitor.' Junior's two identities breed contempt at home...... his time in Rearden changes how he is seen by others.