### 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{"listsinceblock",
                "\nGet all transactions in blocks since block [blockhash], or all transactions if omitted.\n"
                "If \"blockhash\" is no longer a part of the main chain, transactions from the fork point onward are included.\n"
                "Additionally, if include_removed is set, transactions affecting the wallet which were removed are returned in the \"removed\" array.\n",
                {
                    {"blockhash", RPCArg::Type::STR, RPCArg::Optional::OMITTED_NAMED_ARG, "If set, the block hash to list transactions since, otherwise list all transactions."},
                    {"target_confirmations", RPCArg::Type::NUM,  "1", "Return the nth block hash from the main chain. e.g. 1 would mean the best block hash. Note: this is not used as a filter, but only affects [lastblock] in the return value"},
                    {"include_watchonly", RPCArg::Type::BOOL,  "true for watch-only wallets, otherwise false", "Include transactions to watch-only addresses (see 'importaddress')"},
                    {"include_removed", RPCArg::Type::BOOL,  "true", "Show transactions that were removed due to a reorg in the \"removed\" array\n"
            "                                                           (not guaranteed to work on pruned nodes)"},
                },
                RPCResult{
            "{\n"
            "  \"transactions\": [\n"
            "    \"involvesWatchonly\": xxx, (bool) Only returns true if imported addresses were involved in transaction.\n"
            "    \"address\":\"address\",    (string) The bitcoin address of the transaction.\n"
            "    \"category\":               (string) The transaction category.\n"
            "                \"send\"                  Transactions sent.\n"
            "                \"receive\"               Non-coinbase transactions received.\n"
            "                \"generate\"              Coinbase transactions received with more than 100 confirmations.\n"