I have little question about canvassing in suits.

I tailored a suit for myself with 90:10 wool silk blend just 2-week ago and went for a fittings last week (and going to receive it next week). The tailor only offers partial canvas and I know that the remaining part will definitely be fused. But, I noticed the part under the canvas was fused as well on the same thickness with the lower part.

Is this normal for half canvas to be fused fully supported with a half canvas on top?

Or that the fully fused is normally thicker?