I'm not sure I understand - are these two fish that have been long term tankmates or are they just in the same tank at the lfs? If it's the latter I would disagree - unless you can get a school (6 or more) I would say you should stick with just one (unless you have a huge aquarium). They tend to fight amongst themselves and can do quite a bit of damage when they want to. If you only have two I would worry that the dominant one will kill the other.