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.
connOptions.vWhiteBinds.push_back(addrBind);
    }
    for (const auto& net : gArgs.GetArgs("-whitelist")) {
        CSubNet subnet;
        LookupSubNet(net.c_str(), subnet);
        if (!subnet.IsValid())
            return InitError(strprintf(_("Invalid netmask specified in -whitelist: '%s'"), net));
        connOptions.vWhitelistedRange.push_back(subnet);
    }
    connOptions.vSeedNodes = gArgs.GetArgs("-seednode");
    
    connOptions.m_use_addrman_outgoing = !gArgs.IsArgSet("-connect");
    if (!connOptions.m_use_addrman_outgoing) {
        const auto connect = gArgs.GetArgs("-connect");
        if (connect.size() != 1 || connect[0] != "0") {
            connOptions.m_specified_outgoing = connect;
        }
    }
    if (!connman.Start(scheduler, connOptions)) {
        return false;
    }
    
    SetRPCWarmupFinished();
    uiInterface.InitMessage(_("Done loading"));
#ifdef ENABLE_WALLET
    StartWallets(scheduler);
#endif
    return true;
}