### Describe the issue

Testing in bitcoin 0.13.0, calling `bitcoin-cli listsinceblock x` is outputting all double-spent transactions that are in the wallet, even those that were double-spent well and truly before x.
### Is the issue reproducible?

Yes
#### List steps to reproduce below:
1.   Create a double-spend send to your wallet (easiest using bip125)
2.   Wait until one confirms, and then wait a few more blocks
3.   Run `bitcoin-cli listsinceblock $(bitcoin-cli getbestblockhash)` and it will output the double spent transaction
### Expected behavior

The double-spent transaction that was conflicted before the block hash should be filtered

return NullUniValue;
    }
            RPCHelpMan{"settxfee",
                "\nSet the transaction fee per kB for this wallet. Overrides the global -paytxfee command line parameter.\n",
                {
                    {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "The transaction fee in " + CURRENCY_UNIT + "/kB"},
                },
                RPCResult{
            "true|false        (boolean) Returns true if successful\n"
                },
                RPCExamples{
                    HelpExampleCli("settxfee", "0.00001")
            + HelpExampleRpc("settxfee", "0.00001")
                },
            }.Check(request);
    auto locked_chain = pwallet->chain().lock();
    LOCK(pwallet->cs_wallet);
    CAmount nAmount = AmountFromValue(request.params[0]);
    CFeeRate tx_fee_rate(nAmount, 1000);
    if (tx_fee_rate == CFeeRate(0)) {
        
    } else if (tx_fee_rate < pwallet->chain().relayMinFee()) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than min relay tx fee (%s)", pwallet->chain().relayMinFee().ToString()));
    } else if (tx_fee_rate < pwallet->m_min_fee) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than wallet min fee (%s)", pwallet->m_min_fee.ToString()));
    }
    pwallet->m_pay_tx_fee = tx_fee_rate;
    return true;
}
static UniValue getbalances(const JSONRPCRequest& request)