well the suspected male definitely looks like a male to me but give the smaller one some more time to grow before we try sexing it. Another inch or so and we should be able to tell for sure.
The best way to do it is by looking to see if there are spots above the lateral line on the fins or body but this doesn't happen until they reach 4-5". I made have made this mistake personally when I was trying to find a female for my male I accidentally bought a 2nd male so I traded him in a month or so later
The shemale is much more outgoing. She actually gets along decently with a group of tinfoil barbs and a pleco. The male is totally brutal and kills everything except the shemale but hides ALL day.