You should get one of these and sweep the impedance curve of each speaker in the enclosure to see the differences and correlate them to frequency response differences:
https://www.daytonaudio.com/product/1650/dats-v3-computer-based-audio-component-test-system
It will store up to 20 different impedance sweeps, all of which can be displayed simultaneously or individually, and saved to a pdf if desired, like the sweep of my 72 Marshall 4x12 I've attached to this post.
https://www.daytonaudio.com/product/1650/dats-v3-computer-based-audio-component-test-system
It will store up to 20 different impedance sweeps, all of which can be displayed simultaneously or individually, and saved to a pdf if desired, like the sweep of my 72 Marshall 4x12 I've attached to this post.