I would seperate them. BGK's really dont get along with each other due to territory dispute witch will keep them fighting usually till death from what I seen personally in the past. 1 BGK = okay..........2 or more = trouble.
I had 4 BGK together in a very large community tank for around 6 months without any trouble. Suddendly it started. The biger one made it and a smallish one was saved by me in the last minute....
This is a very bad idea, mostly if you put 2 or more in a tank they will bite off the other bgk's tail or fins. Whoever wins might survive if he has no injury at all.