Opening two of the same wallet (tested in v0.18.0 of bitcoin-qt 64 bit) will cause a database collision, and will crash the program.

`[marshall@likon] {21:21} [~] $ bitcoin-0.18.0/bin/bitcoin-qt `
`terminate called after throwing an instance of 'std::runtime_error'  what():  BerkeleyBatch: Can't open database 8204388-wallet.dat (duplicates fileid 8b1c090000000800e25686350000000000000000 from 1352491-wallet.dat)`
`Aborted (core dumped)`

I have been able to reproduce the issue by importing two of the same wallet (with different filenames).
{
    if (!CWallet::Verify(chain, location, false, error, warnings)) {
        error = "Wallet file verification failed: " + error;
        return nullptr;
    }
    std::shared_ptr<CWallet> wallet = CWallet::CreateWalletFromFile(chain, location, error, warnings);
    if (!wallet) {
        error = "Wallet loading failed: " + error;
        return nullptr;
    }
    AddWallet(wallet);
    wallet->postInitProcess();
    return wallet;
}
std::shared_ptr<CWallet> LoadWallet(interfaces::Chain& chain, const std::string& name, std::string& error, std::vector<std::string>& warnings)
{
    return LoadWallet(chain, WalletLocation(name), error, warnings);
}
WalletCreationStatus CreateWallet(interfaces::Chain& chain, const SecureString& passphrase, uint64_t wallet_creation_flags, const std::string& name, std::string& error, std::vector<std::string>& warnings, std::shared_ptr<CWallet>& result)