People have looked into circle packings with two kinds of circles. Of course they did. Are they fun to look at? Indeed they are:
https://en.wikipedia.org/wiki/File%3A2-d_dense_packing_r1.svg
Just scroll down to find some more! The article is a bit short, but here it is:
https://en.wikipedia.org/wiki/Circle_packing#Unequal_circles

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