Awesome giant picture with even better zoom! It appears to be a single comb, but that happens sometimes with inferior breeding stock, not a big deal. That's why breeding to standard is so difficult/time-consuming and SOP (standard of perfection) chicks are so expensive. And Australia may have different standards anyway.
Six weeks is a tough age to add more babies if they're not about the same age. You're considering 12 week olds? I'm sure people have done it. But very soon those hormones will start kicking in and juveniles are very boisterous and inconsiderate... your youngsters might be at risk. If the farm is willing, is it possible to switch out your current chicks with a new batch? Such a tough call I know, you're probably already attached.
Well you could read up on integration and see what you think for yourself. Mixing adolescents is a bit different than mixing adults, or adding chicks to adults (which is what I prefer). But everyone has probably done every combination so it might be worth a shot!
See But Don’t Touch
The Essential Quarantine
Integrating at 4 weeks old
It would be a bummer if both turn out to be cockerels and you didn't have any pullets to keep. But I don't know if you should rule out them still being pullets... my girls had puffy chests too (full crops)
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and started acting all cockerelly later on (just being kids), so you never really know til they crow... or lay eggs!
I started with 3 chicks because I also thought I would never be able to fit more than that as my first coop was really tiny. But I found an unused spot in my yard that works great and built a custom coop to fit that space!
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I built this gate to contain them to the side yard and my custom coop has 2 runs for easy separation when necessary.
I added 3 more babies last spring (but eventually lost 2 of my original 3) and still plan on adding more again (but no roosters!). You might discover a way to get creative later on too!
Here's a few more pics... just because!
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