All doves coo, both sexes coo aggressively when another bird of the same sex is around. Other than disection or actual observation of egg laying I do not know of any certain way to determine the sex of my doves. Some people say you can feel the vent bones, but I can't tell any difference except when a female is about to lay an egg her bones do move wider apart. Doves will practice homosexual behavior if an opposite sex dove is not present. Later when other birds of opposite sex are introduced all the birds in the cage exhibit hetrosexual behavior to establish dominence.
Doves fight and challenge vigorously to establish dominence.
When a dove is getting beat too badly and starts bleeding or I observe swelling wounds I usually remove it from the cage. Doves do better with seed for food. If you cannot find dove mix, wild birdseed with suffice, but I was told by calling WSU School of Veternary Sciences that sunflower seed has too much fat for caged bird's health. I think this is a little too rich for the bird diet, but it is all I can find in Helena, Montana.