ESS AMT Heil Tweeters - but different Impedances

I was given these tweeters for free after an amplifier purchase, but realized the two do not have matching impedances. I checked them on the DMM and one shows 3.9 ohm while other shows 7.9.

Looking at the certificates, both are consecutive serial numbers and both played fine when hooked up at low wattage.

I have too many projects to mess with them or experiment but the mismatched impedances concern me that someone else couldnt enjoy them.

what am I looking at here and are they usable for someone?
 

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Through the years the sold replacement diaphragms made of slightly different materials and impedance. The early 8 ohm ones are supposed to be the best but can burn up with too much power. The thicker later ones are not as good. If your serial numbers are sequencuntil then one has been replaced.
 
I talked to the original owner. He said he did replace one but did not realize they may have been different impedances. While talking to him he offered me the original Heil Horned speakers he had been using the AMTs with.

only issue I have now is, the AMT need to be the same impedance at 8 ohms to work with the crossover network and speaker design he has.
Wondering if ESS is able to help me get an 8 ohm to match the impedance I need.
Worst case scenario I could make both of them 4 ohm and use an active crossover network.