Telling males from females is pretty hard to do unless they are extra large or ya catch them in the act. Extra large males will start to develop a small bump on their forehead much like how a flowerhorn will start to grow their kok. Yours I would say are still a bit too small to accurately ID as male or female just by looks alone. As for egg fertility if the are snow white they are duds if they are clear they should be fertile. Also yes it's not too uncommon for females to pair up or for males to pair up. Lol I had a male pair of tinfoil Barb's that would crop dust eachother, it was weird, gross and cool all in one. Lol nothing like having you fish tank turn into a giant snow globe.
Btw a word of advice, your should probably separate the odd man out from the group otherwise their may be allot of infighting in the future. Also if ya have a pleco in the tank or cories I would recommend setting up a small lamp light to shine down ontop of the eggs at night. It helps deter night time scavengers from predating on the eggs while the parents rest.
