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).
{
    QMutexLocker locker(&m_mutex);
    
    if (!m_wallets.empty()) {
        std::string name = wallet->getWalletName();
        for (WalletModel* wallet_model : m_wallets) {
            if (wallet_model->wallet().getWalletName() == name) {
                return wallet_model;
            }
        }
    }
    
    WalletModel* wallet_model = new WalletModel(std::move(wallet), m_node, m_platform_style, m_options_model, nullptr);
    
    wallet_model->moveToThread(thread());
    wallet_model->setParent(this);
    m_wallets.push_back(wallet_model);
    
    
    
    const bool called = QMetaObject::invokeMethod(wallet_model, "startPollBalance");
    assert(called);
    connect(wallet_model, &WalletModel::unload, this, [this, wallet_model] {