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).
}
        if (block_hash == stop_block) {
            break;
        }
        {
            auto locked_chain = chain().lock();
            Optional<int> tip_height = locked_chain->getHeight();
            if (!tip_height || *tip_height <= block_height || !locked_chain->getBlockHeight(block_hash)) {
                
                
                break;
            }
            
            block_hash = locked_chain->getBlockHash(++*block_height);
            progress_current = chain().guessVerificationProgress(block_hash);
            
            const uint256 prev_tip_hash = tip_hash;
            tip_hash = locked_chain->getBlockHash(*tip_height);
            if (stop_block.IsNull() && prev_tip_hash != tip_hash) {
                
                progress_end = chain().guessVerificationProgress(tip_hash);
            }
        }
    }
    ShowProgress(strprintf("%s " + _("Rescanning...").translated, GetDisplayName()), 100); 
    if (block_height && fAbortRescan) {
        WalletLogPrintf("Rescan aborted at block %d. Progress=%f\n", *block_height, progress_current);
        result.status = ScanResult::USER_ABORT;
    } else if (block_height && chain().shutdownRequested()) {
        WalletLogPrintf("Rescan interrupted by shutdown request at block %d. Progress=%f\n", *block_height, progress_current);