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).
int& nChangePosInOut, std::string& strFailReason, const CCoinControl& coin_control, bool sign)
{
    CAmount nValue = 0;
    const OutputType change_type = TransactionChangeType(coin_control.m_change_type ? *coin_control.m_change_type : m_default_change_type, vecSend);
    ReserveDestination reservedest(this, change_type);
    int nChangePosRequest = nChangePosInOut;
    unsigned int nSubtractFeeFromAmount = 0;
    for (const auto& recipient : vecSend)
    {
        if (nValue < 0 || recipient.nAmount < 0)
        {
            strFailReason = _("Transaction amounts must not be negative").translated;
            return false;