Then what would the point of paying for the extra output capabilities of the more powerful sub if you can never use it? There are scenarios where blending different subs would be viable (the most common is using one near field), but it is often best practice to use two identical subs.
Edit: misread your post - thought you said turn the stronger sub down. No, you want to level match your subs at your LP, so unless you place the smaller one near field, it will limit the larger one.
As for your logic, I'm not sure where you get the idea that mismatched speakers will provide a better sound. The point of having multiple subs is for the increased headroom (3-6db over a single) and smoothing the frequency response in your room, which is best achieved by identical subs.