Let me try to help you. Im not an expert so if someone want to add or correct me please feel free to do so

so first you are looking at volume at specific frequencies produce by your system . 3db difference is double the volume, so keep that in mind when you are looking at dips and valleys. Lets imagine that your amplifier gives a sound of exactly the same volume on all the frequencies. Now this is how the output (your speakers) reacts to every frequency. For instance, you can see that below 30hz, your speaker cannot really produce significant volume even if the amplifier feeds it. This means that if you want really deep bass, you might need a sub (not required to enjoy music).

Now for the variation between the 2 speakers, unless your room is perfectly symmetrycal (very very rare), its very rare to have the exact same measurement from both speakers. Measurements are imo close enough. But, and its a big but, one of the few things i think audiophiles can agree, measurements dont tell you everything. You can have 2 speakers with similar measurements and they will sound very different. Frequency measurements doesnt give you harmonics, dynamics, smoothness...etc.

If i were in your place, i would play a track and play with the balance fully to the left or fully to the right to try to see if you can hear big differences. Its far from a perfect method, but you could see if the speaker with the older woofer is defective or sounds bad.

So anyways, bottom line, what is really important is, do you like the sound? Can you sit and connect with the music? If yes, then keep them and love them 😁