Back with the stupid questions - adductor and abductor disparity

Hello again!

So I've now been going to the gym and using weight machines for 3 or 4 weeks and I am really enjoying it despite my hilariously feeble upper body (and everything else but especially my upper body). I want to ask specifically about adductor and abductor machines though please, because I have a huge disparity in ability there and I feel like something makes sense and my friend tells me it does not.

So, on the abduction machine I do 3 sets of 12 at 75kg. I am fairly confident I could do decently higher than that too because I am nowhere near failure on those. But, on the abduction machine I struggle to complete 3x12 at 50kg, and that's with split sets, I still can't fully finish the last 2 or 3 reps (not entirely true as I did for the first time on tuesday, but usually I can't). My thoughts on this are that although I think I could probably stick at least another 10kg on the abductor, I feel like if I do that and continue to train those muscles, it will be ultimately counterproductive to training the adductors because they work together/in opposition. So in my head, it makes sense to keep the abductors lower until my adductors have caught up a bit, then train both with the same effort (I don't mean the same weight because my - admittedly minimal - understanding is that the adductors should be about 80-90% of abductors, but I think I'm currently more like 60%).

Have I got this all wrong?