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.
{
    LOCK(cs_db);
    assert(mapFileUseCount.count(strFile) == 0);
    u_int32_t flags = DB_SALVAGE;
    if (fAggressive)
        flags |= DB_AGGRESSIVE;
    std::stringstream strDump;
    Db db(dbenv.get(), 0);
    int result = db.verify(strFile.c_str(), nullptr, &strDump, flags);
    if (result == DB_VERIFY_BAD) {
        LogPrintf("CDBEnv::Salvage: Database salvage found errors, all data may not be recoverable.\n");
        if (!fAggressive) {
            LogPrintf("CDBEnv::Salvage: Rerun with aggressive mode to ignore errors and continue.\n");
            return false;
        }
    }
    if (result != 0 && result != DB_VERIFY_BAD) {
        LogPrintf("CDBEnv::Salvage: Database salvage failed with result %d.\n", result);
        return false;
    }