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).
{
    const std::string walletFile = WalletDataFilePath(location.GetPath()).string();
    
    std::vector<CWalletTx> vWtx;
    if (gArgs.GetBoolArg("-zapwallettxes", false)) {
        chain.initMessage(_("Zapping all transactions from wallet...").translated);
        std::unique_ptr<CWallet> tempWallet = MakeUnique<CWallet>(&chain, location, WalletDatabase::Create(location.GetPath()));
        DBErrors nZapWalletRet = tempWallet->ZapWalletTx(vWtx);
        if (nZapWalletRet != DBErrors::LOAD_OK) {
            error = strprintf(_("Error loading %s: Wallet corrupted").translated, walletFile);
            return nullptr;
        }
    }
    chain.initMessage(_("Loading wallet...").translated);
    int64_t nStart = GetTimeMillis();
    bool fFirstRun = true;
    
    
    std::shared_ptr<CWallet> walletInstance(new CWallet(&chain, location, WalletDatabase::Create(location.GetPath())), ReleaseWallet);
    DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
    if (nLoadWalletRet != DBErrors::LOAD_OK) {