Since that is a Riolis kit I'm guessing the thread is wool, like very very thin yarn. So yes, you'd use the whole strand when it asks for one thread because it does not seperate. You'd use two then if it asked for two. It's not the type of thread you seperate.
That's a very pretty picture. Hope you show pictures of your progress once you get it going.
Hope that helped.

Thank you!

You're welcome. I had a hard time getting used to the thread on my first Riolis kit. It was baby penguins so the different texture was a nice addition to the finish.