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).
{
    m_spk_man = pwallet->GetScriptPubKeyMan(type, internal);
    if (!m_spk_man) {
        return false;
    }
    if (nIndex == -1)
    {
        m_spk_man->TopUp();
        CKeyPool keypool;
        if (!m_spk_man->GetReservedDestination(type, internal, address, nIndex, keypool)) {
            return false;
        }
        fInternal = keypool.fInternal;
    }
    dest = address;
    return true;
}
void ReserveDestination::KeepDestination()