They may have two pilots in the machine but I very much doudt they will have got the relevant equipment fit and permissions for multicrew time be able to be logged.
If they don't have multicrew approval for a SPA then only the PIC can log anything on a normal flight.
Again for someone that has no intention of going airline this won't be a problem but if you looking to build hours to then move on it won't be much use. And if you decide to log co-pilot or PICUS or some such rubbish as the second pilot expect to have serious problems with your log book later on in life.