I’ve raised several groups of Blue Dempseys and I find the males to be just as aggressive and territorial with one another as Standard Dempseys tend to be. So just like with other Cichlids, I wouldn’t suggest keeping multiple males in the same tank, especially if you have females of the same species in the tank.
My stronger Blue Dempseys have proven to be just as tough as my standards, and therefore do well with the same kind of tankmates as standard Dempseys.