Bluetooth CBPeripheralManager has two identical service

I user the code

[_peripheralManager stopAdvertising];
[_peripheralManager removeAllServices];

....................................................................

 _service = [[CBMutableService alloc]initWithType:[CBUUID UUIDWithString:KServiceUUID] primary:YES];
    [_service setCharacteristics:@[readwriteCharacteristic, notiyCharacteristic]];
    [_peripheralManager addService:_service];

    [_peripheralManager startAdvertising:@{
        CBAdvertisementDataServiceUUIDsKey :@[[CBUUID UUIDWithString:advId]],
        CBAdvertisementDataLocalNameKey : KLocalName,
    }];

sometimes has has two identical service
One of them cannot work，

_peripheralManager removeService does not work

why? How do I delete that that can t work？ thanks