### 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

{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
            RPCHelpMan{"sendtoaddress",
                "\nSend an amount to a given address." +
                    HelpRequiringPassphrase(pwallet) + "\n",
                {
                    {"address", RPCArg::Type::STR, RPCArg::Optional::NO, "The bitcoin address to send to."},
                    {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "The amount in " + CURRENCY_UNIT + " to send. eg 0.1"},
                    {"comment", RPCArg::Type::STR, RPCArg::Optional::OMITTED_NAMED_ARG, "A comment used to store what the transaction is for.\n"
            "                             This is not part of the transaction, just kept in your wallet."},
                    {"comment_to", RPCArg::Type::STR, RPCArg::Optional::OMITTED_NAMED_ARG, "A comment to store the name of the person or organization\n"
            "                             to which you're sending the transaction. This is not part of the \n"
            "                             transaction, just kept in your wallet."},
                    {"subtractfeefromamount", RPCArg::Type::BOOL,  "false", "The fee will be deducted from the amount being sent.\n"
            "                             The recipient will receive less bitcoins than you enter in the amount field."},
                    {"replaceable", RPCArg::Type::BOOL,  "wallet default", "Allow this transaction to be replaced by a transaction with higher fees via BIP 125"},
                    {"conf_target", RPCArg::Type::NUM,  "wallet default", "Confirmation target (in blocks)"},