Counting error

Hello, if set the stats with the code, the startstats will be automaticly setted too, but why? I'm not setting the startstats again.

PHP:

private static HashMap<Player, Statistik> startstats = new HashMap<Player, Statistik>();
private static HashMap<Player, Statistik> stats = new HashMap<Player, Statistik>();

public static void onJoin(Player player) {
    startstats.put(player, new Statistik(0, 0, 0, 0, 0, 0));
    stats.put(player, new Statistik(0, 0, 0, 0, 0, 0));
}

public static void setStats(Player player, Statistik statistik){
        if(stats.containsKey(player)){
            Bukkit.getLogger().info("Stats: " + getStatistik(player).getKills());
            Bukkit.getLogger().info("Start: " + startstats.get(player).getKills());
            stats.remove(player);
        }
        stats.put(player, statistik);
        Bukkit.getLogger().info("Stats: " + getStatistik(player).getKills());
        Bukkit.getLogger().info("Start: " + startstats.get(player).getKills());
    }

public static Statistik getStatistik(Player player){
        if(stats.containsKey(player)) return stats.get(player);
        return null;
    }

public static void update(Player player){
    Statistik killer = StatsSystem.getStatistik(player);
    killer.setKills(killer.getKills() + 1);
    killer.setCoins(killer.getCoins() + StatsSystem.getCoinsProKill());
    killer.setPunkte(killer.getPunkte() + StatsSystem.getPunkteProKill());
    StatsSystem.setStats(player, killer);
}