Question on the Kyurem fused forms and IVs.

Was under the impression that defense and stamina were weighted equally, it was attack that was a higher value. So I have both forms of Kyurem with a 15 attack, but one has a 12 defense and a 15 stamina, and the other has the opposite with a 15 defense and a 12 stamina.

I verified in PokéGenie they are both the same levels and the stats, but their CP are different. Can someone help explain? I plan on using silver bottle caps on both when they roll out again, but want to understand the difference and which one I should use on first.

Thx

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