The RPC docs are now enforced to specify the json type of the args and results at compile time. However, some help texts contain the type twice. (E.g. https://github.com/bitcoin/bitcoin/pull/17809#discussion_r386295217 ). The duplicate type in the description should be removed.

Duplicates can be found with this command:

```sh
git grep --extended-regexp  'RPC.*(ARR|OBJ).*json (array|object)' src/rpc/ src/wallet/rpc*
```

#### Useful skills:

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if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
            RPCHelpMan{"sethdseed",
                "\nSet or generate a new HD wallet seed. Non-HD wallets will not be upgraded to being a HD wallet. Wallets that are already\n"
                "HD will have a new HD seed set so that new keys added to the keypool will be derived from this new seed.\n"
                "\nNote that you will need to MAKE A NEW BACKUP of your wallet after setting the HD wallet seed." +
                    HelpRequiringPassphrase(pwallet) + "\n",
                {
                    {"newkeypool", RPCArg::Type::BOOL,  "true", "Whether to flush old unused addresses, including change addresses, from the keypool and regenerate it.\n"
            "                             If true, the next address from getnewaddress and change address from getrawchangeaddress will be from this new seed.\n"
            "                             If false, addresses (including change addresses if the wallet already had HD Chain Split enabled) from the existing\n"
            "                             keypool will be used until it has been depleted."},
                    {"seed", RPCArg::Type::STR,  "random seed", "The WIF private key to use as the new HD seed.\n"
            "                             The seed value can be retrieved using the dumpwallet command. It is the private key marked hdseed=1"},
                },
                RPCResults{},
                RPCExamples{
                    HelpExampleCli("sethdseed", "")
            + HelpExampleCli("sethdseed", "false")
            + HelpExampleCli("sethdseed", "true \"wifkey\"")
            + HelpExampleRpc("sethdseed", "true, \"wifkey\"")
                },
            }.Check(request);
    LegacyScriptPubKeyMan& spk_man = EnsureLegacyScriptPubKeyMan(*pwallet, true);
    if (pwallet->chain().isInitialBlockDownload()) {
        throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Cannot set a new HD seed while still in Initial Block Download");
    }
    if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Cannot set a HD seed to a wallet with private keys disabled");