Contd. from above ...
What some people term as "Dual PIC" is basically a flight in which a legally Licensed pilot is getting trained by the person on the RHS (who happens to be a legally certified flight instructor).
In other ICAO countries, this so called "dual PIC" time is logged as P1 UNDER SUPERVISION/TRAINING.
Which is why you will not find this (P1 Under Supervision/Training) or P1/US or P1/UT column in FAA logbooks.
You will find this column in JAA/other ICAO countries pilot logbooks.