I already have CSPX but am very tempted to buy QQQ as well. Is it too over-lapping ? if yes, are there any other etf's which can go together with CSPX without over-lapping ?

As the market has decreased a bit, was thinking of buying QQQ but i already have CSPX so am mighty confused if it makes sense or probably focus on some other etf which don't overlap but QQQ has performed so well recently so a bit difficult to ignore.