With Gourami... Males and females both tend to fight with each other and I have always kept to a "one Gourami rule per tank". I know there are many incidents of members keeping several together but I think in most cases they are in fairly large tanks which allows for a small school of them 6-7 which helps settle aggression. Usually most of the Gourami sold in the LFS are the Males. They are the colorful ones.. the females are quite drab. So if you bring 2 very pretty ones home, they are likely both males and you will immediately have a dominance issue in your tank. I even had 2 Pearl Gourami, the gentlest of Gouramis fight and chase each other in my 75 gallon... even in 48 inches of water the one was unable to get away from the other.
Hope this helps.