Yes, you can stack notables from cluster jewels.

Do notable passives stack Poe?

Yes, Cluster Jewel notables can stack. They are the only kind of Notables that can stack (anointing a Passive Tree notable AND allocating it won't "double" its effect, in other words).

Can you roll cluster jewels?

It had to be rolled as one of the suffixes on your Cluster Jewel and could come in a 1 or 2-socket variant for Large Cluster Jewels. ... They now come on the base items 100% of the time and always roll 2 sockets on a Large and a single socket on Medium and Small Cluster Jewels.