I was thinking maybe 8 weeks... My first thought when I looked at the pictures is that they looked a bit dirty so I wasn't sure on the feather color either. They can still look like palms even if they are a mix. I had a Palm hen with some red on her too, they only tom I had was a Narrigansett. She hatched out a clutch that were mostly Bronze but there was one that looked like a pure Palm. So even if they are a mix, they could end up looking pure.
If they are the same age, they could be a pair judging by the heavier legs on the one with dark spots on the wing feathers. Time will tell...
And I have to agree with Nava, it's a good idea to quarantine new birds for a month or so to make sure you aren't bringing anything into your flock. Especially if you are buying from a swap or an auction. I am not saying that everyone is unscrupulous, but there are people who know that they have something wrong with their flock and sell anything not showing symptoms yet. Better to be safe...