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).
WalletLogPrintf("AddToWallet %s  %s%s\n", wtxIn.GetHash().ToString(), (fInsertedNew ? "new" : ""), (fUpdated ? "update" : ""));
    
    if (fInsertedNew || fUpdated)
        if (!batch.WriteTx(wtx))
            return false;
    
    wtx.MarkDirty();
    
    NotifyTransactionChanged(this, hash, fInsertedNew ? CT_NEW : CT_UPDATED);
#if HAVE_SYSTEM
    
    std::string strCmd = gArgs.GetArg("-walletnotify", "");
    if (!strCmd.empty())
    {
        boost::replace_all(strCmd, "%s", wtxIn.GetHash().GetHex());
#ifndef WIN32
        
        
        
        
        
        boost::replace_all(strCmd, "%w", ShellEscape(GetName()));
#endif
        std::thread t(runCommand, strCmd);
        t.detach(); 
    }
#endif
    return true;
}
void CWallet::LoadToWallet(CWalletTx& wtxIn)