breeding parakeets??

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I think I may have started breeding parakeets unknowingly , I just got a new one for me and it had its own cage next to my sons who we know is a boy since the thing on his nose is blue ( im told this is the sign of a boy) and since it got cold and they seemd to always be chirping at eachother i figured I would let them have a play date , my new bird has no color above the beak , so im wondering if they are both male and female what should i do ?? do you need special nesting stuff in the cage should i take my bird out and put her back in her own cage ?? im lost ! ~M~