Royal Canin does produce "junior" food... but not in the USA... yes it is produced internationally, no it isn't sold in every country.
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The word junior depends on it's context between dog food companies. Junior could be switched for 'puppy' or 'medium size' also. Junior food could just mean the word 'junior' that is written on the bag.
When selecting something to feed your dog, it would obviously give you more information to look at the ingredients list on the back rather than whatever is printed on the front of the bag.