I am new to chickens - only 2 years into raising them but this year we are also trying ducks. My husband wanted ducks. We went to Tractor Supply and bought 6 mallards. Ours look just like yours. We even have 2 black ones like yours. They are very sweet and friendly. The Rouen ducks look the same but they were not as friendly as the Mallards. Hopefully we have Mallards - that is what my husband wanted.
The black striped ones are swedish. I bought some at my local store too. Apparently blue swedish ducks will give you 50% blue, 25% black and 25% silver offspring. Im guessing those are silver, as I have a blue duckling several blacks and one like that.
Last year we had a Blue Swede that was all black when we got it.
On a side note, DH came home tonight and I never said a word. I saw him walk to the garage and then come back in the house. I slyly glanced tot he side as he was trying to form the question. How did we get more ducks? I told him the original 2 were lonely. He just laughed at me and walked back out