Most fish like tetras and danios will hang out with fish that aren't the same but similar. It isn't the best thing but they will "school" for protection. It will probably be safe to get a different type of danio, though I find a larger school of the same fish looks a little more exciting. But that's just my opinion.
Also most fish once in a tank without any preditors, after awhile will not form tight school, just loose associtations. That doesn't mean they still don't want the company, but don't be surprised when they don't constantly hang out together.