Log PIC time, but not SOLO time any time you are acting as pilot in command of an aircraft category class or type for which you are already rated and you have anyone else on board the aircraft wih you regardless of their status as a pilot or passenger. for example... you take a non pilot friend with you your logging it as PIC time but not solo because your not alone.
the only time you would be flying with someone else and NOT log it as PIC time would be IF you are flying with an instructor who is teaching you to operate a category, class or type of aircraft for which you are NOT already rated.
therfore, if you already have your private single engine land and youre with an instructor doing a lesson that is working on your commercial and your operating a single engine land aircraft - by all means log it as PIC AND DUAL - as long as you are already rated in the aircraft being flown.
If you have your private and commercial single engine land - and flying with an instructor who is instructing you for your multi engine rating - you may NOT log it as PIC because you are not yet rated in a multi engine aircraft.
log Solo any time you are the SOLE OCCUPANT OF THE AIRCRAFT. of course solo time would also go toward PIC as well... if your log book differenciates 2 seperate columns for SOLO and PIC time ... Any time you are solo you are also PIC... but when you are PIC doesnt necessarily mean you are solo...
get it?? ;)