It's a very good question,as it provides room to learn and know what is absolutely never okay!Keeping hamsters of different species together is never acceptable,as it will not end well.Even keeping hamsters of the same species is incredibly difficult(and most often ends badly in some way).
This is especially important when you mention Syrians being kept with any hamster at all,since they're entirely solitary as a species and must never be kept with any other hamster.I know some pet stores have really messed up by doing these things,but it is never okay and it should never be done
