Hopefully any 121 interviewer, after seeing hundreds of logbooks, understands that the regulations allow time to be logged in nonsensical ways.

While you can legitimately and legally log anything the regs allow you to, if you know you're headed for a 121 career, it might be wise to keep separate totals in a spreadsheet for things like the simultaneous dual received/PIC question. That way you can do the math along the way and not have hours of adding to do the night before your first interview.