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).
ShowProgress(strprintf("%s " + _("Rescanning...").translated, GetDisplayName()), std::max(1, std::min(99, (int)(m_scanning_progress * 100))));
        }
        if (GetTime() >= nNow + 60) {
            nNow = GetTime();
            WalletLogPrintf("Still rescanning. At block %d. Progress=%f\n", *block_height, progress_current);
        }
        CBlock block;
        if (chain().findBlock(block_hash, &block) && !block.IsNull()) {
            auto locked_chain = chain().lock();
            LOCK(cs_wallet);
            if (!locked_chain->getBlockHeight(block_hash)) {
                
                
                
                
                result.last_failed_block = block_hash;
                result.status = ScanResult::FAILURE;
                break;
            }
            for (size_t posInBlock = 0; posInBlock < block.vtx.size(); ++posInBlock) {
                CWalletTx::Confirmation confirm(CWalletTx::Status::CONFIRMED, *block_height, block_hash, posInBlock);
                SyncTransaction(block.vtx[posInBlock], confirm, fUpdate);
            }
            
            result.last_scanned_block = block_hash;
            result.last_scanned_height = *block_height;
        } else {
            
            result.last_failed_block = block_hash;
            result.status = ScanResult::FAILURE;