Shimano 105 front derailleur has some “extra shift” after shifting to small cog I have a new bike (about a month old). It has Shimano 105 2x11 group set.  The shifting works fine but I have noticed something odd on the front derailleur shifting.

I am in the big cog at the front. I shift to the small cog by pushing the lever as far inwards as it will go. It shifts nicely to the small cog. 

However, I can then push the lever inwards some more and the front derailleur will “shift” a bit further. This doesn’t affect the gears at all as far as I can tell. 

I have put the bike on a stand and done this whilst watching the front mech closely and sure enough, I shift to the small cog (really making sure to push the lever all the way across) and I can see the mech move. But then, I push the lever again and it shifts a bit more and the moves a 
My partner has almost the same bike with same group set and her’s does the same thing.

Hopefully I explained that in a way that makes sense. 

Is it normal?
Ben, congratulations on your new bike!

Yes the behavior is normal. The large cog should have a similar setting, i.e. if you don't shift all the way to the small ring, but just click gently, it should move into an intermediate position as well.

This is called "trimming" and is important to allow the chain to access all rear cogs without scratching on the derailleur. The trim position which you access with the extra click is suitable if you are running a lower gear at the back.