df=data.frame(x=c(1,1,2,2,3,3)
              ,y=c(2,3,4,6,2,7))

myuniq=function(df){
  if(NROW(df)<2){
    return(df)
  } else {
    uniq=!apply(apply(df,2,"%in%",df[1,]),1,any)
    return(rbind(df[1,],myuniq(df[uniq,])))
  }
}
myuniq(df)

set.seed(123456)
n=100000
df=data.frame(x=sample(1:10,n,replace = T)
              ,y=sample(1:10,n,replace = T))
# 允許 x,y 同列相等
myuniq(df)
# 不允許 x,y 同列相等
myuniq(df[!(df$x==df$y),])