Any guess on sexing Campbell's ducks?

[Chickies2020]

These guys are 6 weeks old. Any guesses on what sex they are? They'e both still "peeping" - they sound a lot like they did when they were babies, no honks or frog sounds.

 

[TLWR]

Until they get their real voice, you won't be able to tell.

 

[Chickies2020]

Cry. I thought they would have their "duck voice" by now.