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).
}
        nValue += recipient.nAmount;
        if (recipient.fSubtractFeeFromAmount)
            nSubtractFeeFromAmount++;
    }
    if (vecSend.empty())
    {
        strFailReason = _("Transaction must have at least one recipient").translated;
        return false;
    }
    CMutableTransaction txNew;
    txNew.nLockTime = GetLocktimeForNewTransaction(chain(), locked_chain);
    FeeCalculation feeCalc;
    CAmount nFeeNeeded;
    int nBytes;
    {
        std::set<CInputCoin> setCoins;
        auto locked_chain = chain().lock();
        LOCK(cs_wallet);
        {
            std::vector<COutput> vAvailableCoins;
            AvailableCoins(*locked_chain, vAvailableCoins, true, &coin_control, 1, MAX_MONEY, MAX_MONEY, 0);
            CoinSelectionParams coin_selection_params; 
            
            
            
            CScript scriptChange;
            
            if (!boost::get<CNoDestination>(&coin_control.destChange)) {
                scriptChange = GetScriptForDestination(coin_control.destChange);