LAX-SAN-LAX Same Turboprop Aircraft?

I am trying to book a MR that will back-to-back in SAN, which is serviced by UA6342 on an EMB-120. The flight that I'm looking at arrives at 9:04 PM in SAN, then a flight with the same number departs from SAN at 9:24 PM. I assume this is the same plane, so there's no risk to misconnect, but I was curious if anyone knew if my assumption is correct.

If I run into irrops, would my entire second itin be canceled if I miss the SAN-LAX flight?

EDIT: A roundtrip LAX-SAN-LAX with a 20-minute connection can be booked on United's website, so I guess it is the same plane???