"Mark James Boyd"
In the US, I've always logged my PIC and dual time as mutually
exclusive columns (if I got instruction, I was not PIC).

If you are rated in the aircraft.. and receiving additional instruction..
for example an additional rating, or Flight Review, or a local check out for
renting purposes or a check out in a two seater you had never flown
before... you can still log it as PIC and dual received.

Students, flying with the instructor cannot log PIC, well.. they can log it
but it counts for nothing. They can only log dual received.. they can log
PIC when they are solo.

No one really cares what you log, as long as what you log is needed to show
the insurance company and the FAA that you are qualified to meet the
requirements of a rating you are applying for. Or that you are logging your
3 landings in 90 days to be current to carry passengers.

BT