Problema Django #3

###############View##################
        try:
            serie = TblUsuario.objects.get(usu_username=username)
            if serie is None:
                return JSONResponse({"success": False, "response": "El usuario no existe.."}, status=401)
        except TblUsuario.DoesNotExist:
            return JSONResponse({"success": False, "response": "El usuario no existe."}, status=401)

        serializerUser = UserSerializer(serie)

        if serializerUser.data['usu_password'] != password:
            return JSONResponse({"success": False, "response": "Contraseña incorrecta."}, status=401)

        return JSONResponse(serializerUser.data)

###############Serializers###################

class ActionUserSerializer(serializers.ModelSerializer):
    acc_object = ActionSerializer(source='acc', read_only=True)

    class Meta:
        model = TblAccionUsuario
        fields = ('acc', 'usu', 'acc_object')

class UserSerializer(serializers.ModelSerializer):
    action_user_values = ActionUserSerializer(many=True, read_only=True)

    class Meta:
        model = TblUsuario
        fields = ('usu_id', 'per_usu_id', 'usu_username', 'usu_password',
         'usu_fec_creacion', 'usu_activo', 'usu_nombre', 'usu_          apellido1',
         'usu_apellido2', 'usu_email', 'usu_fono_dijo', 'usu_fono_celular',
         'action_user_values')





################Models#########################

class TblAccionUsuario(models.Model):
    acc = models.OneToOneField(TblAccion, models.DO_NOTHING, primary_key=True)
    usu = models.OneToOneField('TblUsuario', models.DO_NOTHING, primary_key=True, related_name='action_user_values')

    class Meta:
        managed = False
        db_table = 'tbl_accion_usuario'
        unique_together = (('acc', 'usu'),)

class TblUsuario(models.Model):
    usu_id = models.AutoField(primary_key=True)
    per_usu_id = models.IntegerField()
    usu_username = models.CharField(max_length=20)
    usu_password = models.CharField(max_length=128)
    usu_fec_creacion = models.DateTimeField(auto_now_add=True)
    usu_activo = models.BooleanField()
    usu_nombre = models.CharField(max_length=50)
    usu_apellido1 = models.CharField(max_length=50)
    usu_apellido2 = models.CharField(max_length=50, blank=True, null=True)
    usu_email = models.CharField(max_length=100, blank=True, null=True)
    usu_fono_dijo = models.CharField(max_length=20, blank=True, null=True)
    usu_fono_celular = models.CharField(max_length=20, blank=True, null=True)

    class Meta:
        managed = False
        db_table = 'tbl_usuario'

##########Error##############
sigos.models.MultipleObjectsReturned: get() returned more than one TblAccionUsuario -- it returned 2!

########Respuesta deseada#############
{ #Datos del usuario
    "usu_id": 52,
    "per_usu_id": 1,
    "usu_username": "admin",
    "usu_password": "xcvcxvcxvcxv",
    "usu_fec_creacion": "2018-08-13T16:23:50.968003Z",
    "usu_activo": true,
    "usu_nombre": "asdsadasd",
    "usu_apellido1": "sdfdsfdsf",
    "usu_apellido2": "dsfsdf",
    "usu_email": "sdfdsfsdf@gmail.com",
    "usu_fono_dijo": "+sdffsdf",
    "usu_fono_celular": "+sdfdsfsdf",
    "action_user_values": [ #Actions User relacionadas al usuario (esto es lo que me da error, cuando son más de uno)
        {
        "acc": 1,
        "usu": 52,
        "acc_object": {
            "acc": 1,
            "cat_acc": 1,
            "id_accion_madre": null,
            "acc_nombre": "Listar",
            "acc_url": "/list",
            "acc_imagen": null,
            "acc_orden": 1,
            "acc_mostrar": true,
            "acc_activa": true,
        },
        {
        "acc": 2,
        "usu": 52,
        "acc_object": {
            "acc": 2,
            "cat_acc": 1,
            "id_accion_madre": null,
            "acc_nombre": "Crear",
            "acc_url": "/new",
            "acc_imagen": null,
            "acc_orden": 2,
            "acc_mostrar": true,
            "acc_activa": true,
        }
    ]
}