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:
    WalletControllerActivity(WalletController* wallet_controller, QWidget* parent_widget);
    virtual ~WalletControllerActivity();
Q_SIGNALS:
    void finished();
protected:
    interfaces::Node& node() const { return m_wallet_controller->m_node; }
    QObject* worker() const { return m_wallet_controller->m_activity_worker; }
    void showProgressDialog(const QString& label_text);
    WalletController* const m_wallet_controller;
    QWidget* const m_parent_widget;
    QProgressDialog* m_progress_dialog{nullptr};
    WalletModel* m_wallet_model{nullptr};
    std::string m_error_message;
    std::vector<std::string> m_warning_message;
};
class CreateWalletActivity : public WalletControllerActivity