new PickupFound[MAX_PLAYERS];

// example:

if(pickupid == 1Pickup)
{
    if(PickupFound[playerid]==0)
    {
        // SendMessage you found 1pickup left 4pickups etc.
        PickupFound[playerid]=1;
    }
    else
    {
        // You Alredy have this pickup...
    }
}

if(pickupid == 2Pickup)
{
    if(PickupFound[playerid]==1)
    {
        // SendMessage you found 2pickup left 3pickups etc.
        PickupFound[playerid]=2;
    }
    else
    {
        // You have alredy have this pickup or don't have 1pickup
    }
}