Pair of bantams- are they both Roos?

Hi everyone! I got Khaleesi and Ellie a few weeks ago from a store down the street, about the same time I got 3 buff silkie hens from a local girl that hatched them. (Khaleesi is on the left in the photo.) K&E like to chest bump and stare at each other, which I chalk up to their being young and feisty. The buffs and these two bantams have formed their own flock, but are now able to roost with the rest of the chickens. My established flock is 2 silkies (one roo), a RIR, a black australorp and a buff- all hens besides the roo, Cupid. Well, Khaleesi crowed this morning, and now I'm beginning to wonder if Ellie isn't a roo too. When they were in the store, Ellie kept escaping from her pen into the pen of a very large and manly RIR roo, and he seemed to like her, which makes me think she isn't a roo. I am going to take Khaleesi back to the store, but I wonder if I should take Ellie too. Do you think she could be a roo, or just a bossy hen? My established roo (he's 2x her size) has chased her around but never caught her, so I really don't know if it is mating attempts or a threat. Can anyone tell me if a hen would fight with a roo, or if I should take them both back? This is too hard! Why can't they all just wear special bracelets to tell us what sex they are!?!