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).
{
    Q_OBJECT
public:
    CreateWalletActivity(WalletController* wallet_controller, QWidget* parent_widget);
    virtual ~CreateWalletActivity();
    void create();
Q_SIGNALS:
    void created(WalletModel* wallet_model);
private:
    void askPassphrase();
    void createWallet();
    void finish();
    SecureString m_passphrase;
    CreateWalletDialog* m_create_wallet_dialog{nullptr};
    AskPassphraseDialog* m_passphrase_dialog{nullptr};
};
class OpenWalletActivity : public WalletControllerActivity
{
    Q_OBJECT
public:
    OpenWalletActivity(WalletController* wallet_controller, QWidget* parent_widget);
    void open(const std::string& path);
Q_SIGNALS:
    void opened(WalletModel* wallet_model);
private:
    void finish();
};
#endif