Depending on sex, you'll want to split them up. The adult Alpha male could turn on any other male at any time. Since these guys are more walkers than swimmers, similar to crayfish, it's footprint, not only water volume, should be considered when tank size is considered, for any species of Macrobrachium shrimp.
Quick notes, you won't get any offspring, without a serious investment in time, their life cycle is similar to Caridina multidentata (Amano shrimp).
The subject shrimp, of the bottom image, appears to be the developing Alpha.