Joining a team when the game is running ruins all lists

[Tom1222322]

Hello, I have this problem, whenever a new player joins an already ongoing game it puts him in one of two teams, but it messes up the other player's team. For example, if I was in team a and someone else was in team b new player who joined the game is placed properly into a new team, but players who were already playing get added to both team a and team b which ruins the game.
My code when the game starts:

            loop {sf.players::*}:
                if {_red} is true:
                    delete {_red}
                    sffjTeamRed(loop-value)
                else:
                    set {_red} to true
                    sffjTeamBlue(loop-value)
    if {sf.running} is false:
        set {_size} to size of {sf.players::*}
        if {_size} > 1:
            set {sf.running} to true
            loop {_size} times:
                if mod(loop-value,2)  is not 0:
                    add {sf.players::%loop-value%} to {sf.teamred::*}
                else:
                    add {sf.players::%loop-value%} to {sf.teamblue::*}

My code, which places a player to a team when the game has already started:

                    if {sf.running} is false:
                        if {sf.firstjoin.%player%} is not set:
                            #game is about to start
                        else:
                            #game is about to start
                    
                    else:
                        #game has already started and new player joins
                        set {sf.loc.beforegame.%player%} to player's location
                        add player to {sf.players::*}
                        set {_size} to size of {sf.players::*}
                        if {_size} > 1:
                            loop {_size} times:
                                if mod(loop-value,2)  is not 0:
                                    add {sf.players::%loop-value%} to {sf.teamred::*}
                                else:
                                    add {sf.players::%loop-value%} to {sf.teamblue::*}
                            send "{@prefix} Tu prisijungei į SkyFlag!"
                            if {sf.teamred::*} contains player:
                                send "{@prefix} Tu esi raudonų komandoje!" to player
                                teleport player to {sf.redspawn}
                                clear player's inventory
                                sfTeamRed(player)
                            if {sf.teamblue::*} contains player:
                                send "{@prefix} Tu esi mėlynų komandoje!" to player
                                teleport player to {sf.bluespawn}
                                clear player's inventory
                                sfTeamBlue(player)