### 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{"rescanblockchain",
                "\nRescan the local blockchain for wallet related transactions.\n"
                "Note: Use \"getwalletinfo\" to query the scanning progress.\n",
                {
                    {"start_height", RPCArg::Type::NUM,  "0", "block height where the rescan should start"},
                    {"stop_height", RPCArg::Type::NUM, RPCArg::Optional::OMITTED_NAMED_ARG, "the last block height that should be scanned. If none is provided it will rescan up to the tip at return time of this call."},
                },
                RPCResult{
            "{\n"
            "  \"start_height\"     (numeric) The block height where the rescan started (the requested height or 0)\n"
            "  \"stop_height\"      (numeric) The height of the last rescanned block. May be null in rare cases if there was a reorg and the call didn't scan any blocks because they were already scanned in the background.\n"
            "}\n"
                },
                RPCExamples{
                    HelpExampleCli("rescanblockchain", "100000 120000")
            + HelpExampleRpc("rescanblockchain", "100000, 120000")