This is a problem I stumbled upon after noticing a pattern in the lab- the measured current was never quite what you'd expect from the turns ratio of either transformer alone, but somewhere in the middle. I used 50:5 nominal turn toroidal CTs with 15 turns in one CT primary and 5 turns in the other primary. This is not a homework question but rather an inquiry as far as whether or not I'd need to use complex models to analyze this situation, or rather lumped wire resistance. To get a good start, notice the opposition of KVL in the secondary with the dot convention. This suggests zero flux in the transformer with the lesser amount of turns and thus simply Is = N1(Ip).