They sky-blue and white is definitely a female. They are called Jeffrey and Julie.
I got them from the same pet store. They don't fight, no, but they push each other away from the seeds - of course if one wants seeds the other would quickly follow. I mean they don't really like each other as they don't feed each other and Julie was obsessed with her own reflection so I removed the mirror as you suggested. Will also find them some nice natural branches today and replace the perches. Is it better across the cage or more on sides?
The cage is 35 x 45 x 90cm.
Thank you for your advise.