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).
latestNow = nSmartTime;
                    }
                    break;
                }
            }
            nTimeSmart = std::max(latestEntry, std::min(blocktime, latestNow));
        } else {
            WalletLogPrintf("%s: found %s in block %s not in index\n", __func__, wtx.GetHash().ToString(), wtx.m_confirm.hashBlock.ToString());
        }
    }
    return nTimeSmart;
}
bool CWallet::AddDestData(WalletBatch& batch, const CTxDestination &dest, const std::string &key, const std::string &value)
{
    if (boost::get<CNoDestination>(&dest))
        return false;
    mapAddressBook[dest].destdata.insert(std::make_pair(key, value));
    return batch.WriteDestData(EncodeDestination(dest), key, value);
}
bool CWallet::EraseDestData(WalletBatch& batch, const CTxDestination &dest, const std::string &key)
{
    if (!mapAddressBook[dest].destdata.erase(key))
        return false;
    return batch.EraseDestData(EncodeDestination(dest), key);
}
void CWallet::LoadDestData(const CTxDestination &dest, const std::string &key, const std::string &value)
{
    mapAddressBook[dest].destdata.insert(std::make_pair(key, value));
}
bool CWallet::GetDestData(const CTxDestination &dest, const std::string &key, std::string *value) const