There's really not much you can do with pairs
Research tends to just point towards not using platforms or levels of any sort,no tubes,no houses with single entrances,etc but it doesn't acknowledge whether or not it is natural(it isn't except with mixed sexes which creates the problem of babies)or that it just doesn't allow the same enrichment and cages are often much smaller than the amount of floor space an individual should have let alone enough floor space for two hamsters.
Considering a robo is a nervous species as is and there are so few potential hiding spaces that are appropriate for pairs,you're ending up with massively stressed hamsters.Not only is there the stress of too little space(even a robo needs a decent amount of space,and pairs being housed in small cages get very little of that compared to a single robo housed in the same or larger),but there's the stress of an unnatural living situation as mentioned(you might prefer it and find it cute,but it isn't a good thing to have stressed hamsters who are more prone to illness and just won't be as happy as they would be alone with more enrichment and more of their own space).