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).
{
    
    
    
    
    auto locked_chain = LockChain();
    LOCK(cs_wallet);
    fFirstRunRet = false;
    DBErrors nLoadWalletRet = WalletBatch(*database,"cr+").LoadWallet(this);
    if (nLoadWalletRet == DBErrors::NEED_REWRITE)
    {
        if (database->Rewrite("\x04pool"))
        {
            for (const auto& spk_man_pair : m_spk_managers) {
                spk_man_pair.second->RewriteDB();
            }
        }
    }
    
    fFirstRunRet = m_spk_managers.empty() && !IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) && !IsWalletFlagSet(WALLET_FLAG_BLANK_WALLET);
    if (fFirstRunRet) {
        assert(m_external_spk_managers.empty());
        assert(m_internal_spk_managers.empty());
    }
    if (nLoadWalletRet != DBErrors::LOAD_OK)
        return nLoadWalletRet;
    return DBErrors::LOAD_OK;
}
DBErrors CWallet::ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256>& vHashOut)