As of #11466 we no longer have any logic to prevent a user from opening a wallet twice in two instances simultaneously. Not only could this break BDB (without the -privdb=false option, which I have really no idea why we even have a tuneable option for that), but we certainly don't have logic to handle such a case gracefully. It was noted in the original PR's description, but somehow was never followed up on before merge.
nScriptCheckThreads = gArgs.GetArg("-par", DEFAULT_SCRIPTCHECK_THREADS);
    if (nScriptCheckThreads <= 0)
        nScriptCheckThreads += GetNumCores();
    if (nScriptCheckThreads <= 1)
        nScriptCheckThreads = 0;
    else if (nScriptCheckThreads > MAX_SCRIPTCHECK_THREADS)
        nScriptCheckThreads = MAX_SCRIPTCHECK_THREADS;
    
    int64_t nPruneArg = gArgs.GetArg("-prune", 0);
    if (nPruneArg < 0) {
        return InitError(_("Prune cannot be configured with a negative value."));
    }
    nPruneTarget = (uint64_t) nPruneArg * 1024 * 1024;
    if (nPruneArg == 1) {  
        LogPrintf("Block pruning enabled.  Use RPC call pruneblockchain(height) to manually prune block and undo files.\n");
        nPruneTarget = std::numeric_limits<uint64_t>::max();
        fPruneMode = true;
    } else if (nPruneTarget) {
        if (nPruneTarget < MIN_DISK_SPACE_FOR_BLOCK_FILES) {
            return InitError(strprintf(_("Prune configured below the minimum of %d MiB.  Please use a higher number."), MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024));
        }
        LogPrintf("Prune configured to target %uMiB on disk for block and undo files.\n", nPruneTarget / 1024 / 1024);
        fPruneMode = true;
    }
    nConnectTimeout = gArgs.GetArg("-timeout", DEFAULT_CONNECT_TIMEOUT);
    if (nConnectTimeout <= 0)
        nConnectTimeout = DEFAULT_CONNECT_TIMEOUT;
    if (gArgs.IsArgSet("-minrelaytxfee")) {
        CAmount n = 0;
        if (!ParseMoney(gArgs.GetArg("-minrelaytxfee", ""), n)) {