### 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

}
UniValue walletprocesspsbt(const JSONRPCRequest& request)
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
            RPCHelpMan{"walletprocesspsbt",
                "\nUpdate a PSBT with input information from our wallet and then sign inputs\n"
                "that we can sign for." +
                    HelpRequiringPassphrase(pwallet) + "\n",
                {
                    {"psbt", RPCArg::Type::STR, RPCArg::Optional::NO, "The transaction base64 string"},
                    {"sign", RPCArg::Type::BOOL,  "true", "Also sign the transaction when updating"},
                    {"sighashtype", RPCArg::Type::STR,  "ALL", "The signature hash type to sign with if not specified by the PSBT. Must be one of\n"
            "       \"ALL\"\n"
            "       \"NONE\"\n"
            "       \"SINGLE\"\n"
            "       \"ALL|ANYONECANPAY\"\n"
            "       \"NONE|ANYONECANPAY\"\n"
            "       \"SINGLE|ANYONECANPAY\""},
                    {"bip32derivs", RPCArg::Type::BOOL,  "false", "If true, includes the BIP 32 derivation paths for public keys if we know them"},
                },
                RPCResult{
            "{\n"
            "  \"psbt\" : \"value\",          (string) The base64-encoded partially signed transaction\n"
            "  \"complete\" : true|false,   (boolean) If the transaction has a complete set of signatures\n"
            "  ]\n"
            "}\n"