Therefore the scenario is it appears to append towards the bak file when designing it, can you really prevent doing might just backup the present version?

here's my code

Server backFromServer = new Server(@"server ip add");
backFromServer.ConnectionContext.LoginSecure = false;
backFromServer.ConnectionContext.Login = "uname";
backFromServer.ConnectionContext.Password = "psd";
Database backFromDb = new Database();
backFromDb = backFromServer.Databases["dbname"];

Backup bkpDatabase = new Backup();
bkpDatabase.Action = BackupActionType.Database;
bkpDatabase.Database = backFromDb.Name;
bkpDatabase.Incremental = false;
bkpDatabase.LogTruncation = BackupTruncateLogType.Truncate;                

BackupDeviceItem bkpDevice = new BackupDeviceItem(@"D:\backupfolder\backup.bak",
                                                  DeviceType.File);

bkpDatabase.Devices.Add(bkpDevice);
bkpDatabase.SqlBackup(backFromServer);

Set Backup.Initialize to true:

"If True, the backup specified becomes the very first backup set around the media, overwriting any existing backup sets around the media. "