This is a recurring question throughout the industry. As far as I can see, the question of logging second pilot time usually only comes up on fixed wing or military. Now, if your sitting in the left seat, then it qualifies as first pilot on certain types. Any of the following would qualify in most countries:
SK61,SK76,BH212/412, Super Puma or any other similar Medium or Heavy. Light/Single engine helicopters do NOT qualify as they are only considered as logable time when with an instructer i.e. Dual
Hope this helps!
Cheers, OffshoreIgor