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 = chain().lock();
        LOCK(cs_wallet);
        
        for (std::pair<const uint256, CWalletTx>& item : mapWallet) {
            CWalletTx& wtx = item.second;
            
            
            
            if (wtx.nTimeReceived > m_best_block_time - 5 * 60) continue;
            std::string unused_err_string;
            if (wtx.SubmitMemoryPoolAndRelay(unused_err_string, true)) ++submitted_tx_count;
        }
    } 
    if (submitted_tx_count > 0) {
        WalletLogPrintf("%s: resubmit %u unconfirmed transactions\n", __func__, submitted_tx_count);
    }
}
 
void MaybeResendWalletTxs()
{
    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
        pwallet->ResendWalletTransactions();
    }
}
/** @defgroup Actions
 *
 * @{
 */
CWallet::Balance CWallet::GetBalance(const int min_depth, bool avoid_reuse) const