CSV

var names []string
scanner := bufio.NewScanner(file)
for scanner.Scan() {
    name := scanner.Text()
    for i := 0; i < 4; i++ {
        names = append(names, name)
    }
}

newFile, _ := os.Create("new_names.csv")
defer newFile.Close()

writer := bufio.NewWriter(newFile)
for _, name := range names {
    _, _ = writer.WriteString(name + "\n")
}