WEACLRS

Rick and Tguag have it right. In your example part 91 allows that you can only log the time in which you are sole manipulator. You would log that time as both PIC and Total Duration of Flight. However, realize that if you are not PIC "responsible for the flight" most airlines will deduct that time from your total PIC. Airlines will still allow it as Total Duration of Flight, just not PIC time. When you fill out apps for airlines they will deduct all of your Dual Recieved time from your PIC time, because in their opinion, the instructor was PIC responsible for the flight. In your example you were sole manipulator of the controls for 1.5 hours of a 2.0 hour flight. You may log the 1.5 hours as PIC and Total Duration of Flight.

Note your log book doesn't have a column "Total Time". From the FAA's perspective "Total Time" doesn't exist. This is confused a lot. The column everyone is referring to is "Total Duration of Flight", with heavy accent on Flight. This is why all simulator or flight training device time can only be logged as Flight Simulator or Flight Training Device Time, and Dual Received, because it's not time which occurs in flight.

If your company is having you fly left seat as captain responsible for the flight, now that PIC time would be valued by airlines.

The FAA used to have a great FAQ document that you could download. It's been removed from the faa.gov site. This question was thoroughly covered in that document as it was constantly being asked.

That said, I do know AirNet effectively has (or used to have) a letter of authorization from the FAA that their pilots flying right seat in the Barons can log that time as SIC because their op specs, approved by the FAA, allow the use of a second pilot in AirNet's operations. But my understanding (which may be wrong) is you would have to fly that flight time while working for Airnet only. Ameriflight and Alpine Air may have a similar authorization.