我的原始数据集df中奶源产地有以下几个标签：
Z1 = c("中国大陆","法国","荷兰","德国","爱尔兰","其它","澳洲/新西兰")
我想把这些国家名称换个说法，利用了下面的语句：
factor(df$奶源产地,levels = Z1,labels = c("中国","欧洲","欧洲","其他","欧洲","大洋洲","欧洲"))
R语言报错：
Error in `levels<-`(`*tmp*`, value = if (nl == nL) as.character(labels) else paste0(labels,  :
  factor level [3] is duplicated


请问这种情况怎么了解决呢？
手动一个一个输入保存感觉有点慢