In this case, that doesn't mean much, because they have different comb types.
The one in back (darker feathers) has a pea comb. That makes the comb small, and usually also makes the wattles small. So even if they are the same gender, the one with a single comb would have a bigger comb and bigger wattles.
The one in front has much more red in the comb & wattles. That could mean the one in back (less red) is female, or it could mean the back one is a male that is developing slower.
You might have one Brahma (pea comb) and one Cochin (single comb)
Some chickens show really odd colors & patterns when they are young, before they grow the correct adult feathers. (And some always look odd, depending on how careless the hatchery has been in selecting their breeding stock.)
Here is an old thread with a photo of a Dark Brahma cockerel (first post):
https://www.backyardchickens.com/threads/hen-or-roo-dark-brahma.685508/
At least to me, the coloring looks similar to the coloring of your darker chicken (the one with a pea/small comb).