I would suspect that 2 planets of "same" tech level don't necessarily have the exact same technologies. Meaning, we both probably have radio and rockets, because on discovery of the other, we're inherently motivated to make contact and exchange something, be it bullets or information.
What we exchange is really the key. Culture has a near zero weight over radio. Hollywood exports its TV to an entire planet already. Shipping BayWatch to Mars could happen.
We also could exchange science. Odds are good they'll be farther along in one science and us in another. Trading notes would likely happen.
Militarily, it's be easy to justify building a planetary defense network, than an assault on their planet. It's also lower risk. Mars likely doesn't care that we have a ring of orbital defense platforms around Earth. They can't get to us. But the military can pitch that we need it "just in case they can" without it appearing to be a hostile move against Mars.
We may exchange some one-way payloads with each other. Objects, stuff like that. Ship it to orbit for pick-up by the other party, or some other agreed upon delivery location. Biological samples may be forbidden as that might give away a biological weakness. it's easy to trust a guy on the internet who can't drop a biological attack on your front door.
Eventually, we may setup a Midway station between Mars and Earth for the first direct contact meeting. Something where it's only half the distance for both parties.
Once we find out what the other planet has of value and vice versa, trade will happen. Science will be pushed to develop the technologies to do it, because business will see a way to make money off it.
Our biggest worry would be if we had plenty of something Mars wanted, but they had nothing we wanted. Like our Water. They would be more motivated to take our water, lacking anything of worth to trade us for it.