If they are the identical product: YES, else NO. (check the OPRA code if on TOS)
References below specific to "S&P500 Index"
When you say "monthly", it is not clear if you mean standard monthlies, and for what product. For example, monthlies for S&P500 Index can be AM settled, or PM settled. The PM settled (monthlies) are referenced via SPXPM, where the AM settled is referenced as SPX. Typically, if your referencing SPX products, the "Weekly" designation includes Monday, Wed, and Friday PM settled as well as the EOM PM settled products, which all have the prefix SPXW. The SPXPM products have the same settlement date as the SPX products, however, I know no one that trades the SPXPM, and it has lower liquidity.