Well yea, they know "others" are there. When there are two separate colonies in the house like that, noises you have never heard and will never hear again are made. it is really fascinating, their vocabulary seems to be much larger when they are not able to have physical contact but it is also heart wrecking since they like to do familiar noises we know of like barking and clicking telling each other to come over but they can't....makes you want to speed the intros along faster.
Some original gliders feel intruded on too, they will try to find ways to be more dominant and act silly. Over marking is one of the most obvious ones but when the cages are put near each other they also exhibit excessive attention, monitoring the other cage like a hawk. Other times they might be really intrigued by the others and cling to anything they have been in contact with.
The two groups know that each other is there even though separated. Your original pair probably wonders what this means for them, will they share you? Get half as less time out of the cage? Will they get to live with these strangers or ever meet them or will they live on the other side of the house and never be able to put a face to those calls? If they live together are they going to abide by their rules, after all, they were here first? Are they other sugar gliders or something else? ....They may also think "wait a minute, will we have to share our mealworms?"