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).
WalletLogPrintf("Encrypting Wallet with an nDeriveIterations of %i\n", kMasterKey.nDeriveIterations);
    if (!crypter.SetKeyFromPassphrase(strWalletPassphrase, kMasterKey.vchSalt, kMasterKey.nDeriveIterations, kMasterKey.nDerivationMethod))
        return false;
    if (!crypter.Encrypt(_vMasterKey, kMasterKey.vchCryptedKey))
        return false;
    {
        LOCK(cs_wallet);
        mapMasterKeys[++nMasterKeyMaxID] = kMasterKey;
        WalletBatch* encrypted_batch = new WalletBatch(*database);
        if (!encrypted_batch->TxnBegin()) {
            delete encrypted_batch;
            encrypted_batch = nullptr;
            return false;
        }
        encrypted_batch->WriteMasterKey(nMasterKeyMaxID, kMasterKey);
        for (const auto& spk_man_pair : m_spk_managers) {
            auto spk_man = spk_man_pair.second.get();
            if (!spk_man->Encrypt(_vMasterKey, encrypted_batch)) {
                encrypted_batch->TxnAbort();
                delete encrypted_batch;
                encrypted_batch = nullptr;
                
                
                assert(false);
            }
        }
        
        SetMinVersion(FEATURE_WALLETCRYPT, encrypted_batch, true);
        if (!encrypted_batch->TxnCommit()) {
            delete encrypted_batch;