orphaned block on ethereum

### Description
There are two blocks submitted by miner, but the status is orphaned on databases.
so I can not get any reward.
It is normal? or have other question ?
and my pool sharespersecond about 12 is too low ?

### Steps to Reproduce

1. server log
https://imgur.com/QeINNzX

2. block table
https://imgur.com/a/Xkz2s7x

### Reproduces how often
block 6660876: 2018-11-07 21:37:28
block 6673518: 2018-11-09 18:01:49


### Version
[Server]
Ubuntu 16.04
Latest miningcore as at Thu Oct 25 2018 from master
Parity v2.0.8-stable
Pool hashrate about 28GH/s
Pool sharespersecond about 12
Pool difficulty: 2G
[Client]
Windows 7 or Windows 10
EthDcrMiner64 v11.9


### Additional Information

"pools": [{
        "id": "eth",
        "enabled": true,
        "coin": "ethereum",
        "address": "0x",
        "rewardRecipients": [{
                "type": "op",
                "address": "0x",
                "percentage": 1.0
        }],
        "blockRefreshInterval": 500,
        "clientConnectionTimeout": 600,
        "banning": {
            "enabled": true,
            "time": 600,
            "invalidPercent": 50,
            "checkThreshold": 50
        },
        "ports": {
            "3333": {
                "listenAddress": "0.0.0.0",
                "difficulty": 0.5
            }
        },
        "daemons": [
            {
                "host": "127.0.0.1",
                "port": 8545
            }
        ],
        "paymentProcessing": {
            "enabled": true,
            "minimumPayment": 0.05,
            "minimumPaymentToPaymentId": 5.0,
            "payoutScheme": "PPLNS",
            "payoutSchemeConfig": {
                "factor": 2.0
            },
	"coinbasePassword": "xxxx",
            "keepUncles": false,
            "keepTransactionFees": false
        }
    }]