Use other speakers.
I know that may come off as abrupt, but really, it's the truth.
Home speakers are notorious for being colored, usually in the bass and top ends.
The cabinets are generally tuned to give this kind of skewed sound... and sometimes they are just so cheaply made that they aren't "tuned" at all, but thrown together on an assembly line somewhere, using cheap components... and cheap labor.

If you are looking for a pair of speakers for studio/mixing purposes, then you should get into a pair of speakers that are dedicated to act as such, and that can give you as flat of a response as possible.
Even the cheapest near-fields are gonna be better than using what you are describing you have now.

-d.

Or... find a way to incorporate an equalizer, which isn't as easy as it used to be. (Do you have a tape monitor loop?)

But like Donny, I'd be very concerned about whether any speaker so poorly designed that you can remove a driver and not notice any difference, could be salvaged.

I think the crossover would be my first place to investigate. The actual ones may send wrong sets of frequencies to different section of the speakers cab. Once you validate that the crossover is well balance, swapping speaker or tweeter etc... Another approach would be to tune the output of the crossover with atenuation (with resistors)
If there is no crossover in the towers, start by adding some.

Also try EQ and in the end change speakers and/or Amp...

I get the impression they are in the "white van speaker" range of product. That is, they're junk made for looks, not for sound. Trash them and get real speakers.

speaker placement is very critical. here is how i suggest you set them up. be sure they are at the very bottom of the dumpster so they can be fully covered by the trash.

I'm wondering with a big red flag... if your mix(s) are excessively dipped in the mids there is something more happening here. To not hear significant mid freq difference with two brands of speakers screams more issues than just crap speakers. Being said, buy some Avatones.

Thanks for all your responses (even the sarcastic ones)!Picture of the dumpster was great!
Definately not A speaker of any quality whatsoever.I lined 'em with insulation,had to
put screws in the backs they were vibrating so bad.But what the hell,they were free.I'm
running 500 RMS watts to 'em and they handle it quite well.A good speaker to DJ with.
I'd run A separate PA of course . Don't wanna mess these bad boys up!

which ones are they?