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.
{
    if (activeTxn)
        return;
    
    unsigned int nMinutes = 0;
    if (fReadOnly)
        nMinutes = 1;
    env->dbenv->txn_checkpoint(nMinutes ? gArgs.GetArg("-dblogsize", DEFAULT_WALLET_DBLOGSIZE) * 1024 : 0, nMinutes, 0);
}
void CWalletDBWrapper::IncrementUpdateCounter()
{
    ++nUpdateCounter;
}
void CDB::Close()