The only hamsters that can live in pairs are groups are sibling dwarf hamsters who have grown up together. Introducing another hamster is too risky- even a sibling. Even then they invariably need separating when their hormnes kick in as they grow up as they can start fighting and kill and maim each other. They do absolutely fine living along and will bond with their human
Much safer.
60 x 30 is a bit small for a Robo. It may be fine to begin with while he's settling in but you might want to think about upgrading. With a bigger area you can add more enrichment to make his life interesting - eg more tunnels and floor toys etc, a shelf or platform, a large underground house - that kind of thing. But if he is happy for now then that sounds good. They can take at least 2 weeks to settle into a cage.