My white ducks are getting pale yellow feathers - what breed are they?

[Thisbe]

I recently bought what I thought were Pekins but they are getting pale yellow feathers on their throats and under their 'tails' whereas my 'real' Pekins have stayed all white.. Does anybody know what breed they might be so I can read up on them?

 

[kari_dawn]

Can you provide good, clear pictures? There are so many varieties that without good pictures, it's nearly impossible to tell