Why do Chinese have same name?

CR: https://goo.gl/H42iph

Last September, I traveled to Kyoto, Japan and stayed in a hostel for 2 days. The first person I talked to, besides the guesthouse host, was a girl from Germany. She introduced her name (but I forget what it is now) and then I introduced myself as Wendy. At that moment, I could see a glimpse of surprise in her eyes but she still bought it. Later, I said "You can call me YA-CHUN too. Its my Chinese name. She asked, Why do you have