I made a 2L starter for an upcoming batch of Maibock. I decided to mix the Wyeast Bavarian lager yeast and the White Labs German Lager yeast. I pitched both into a room temperature wort in the 2L flask. They fermented overnight, approximately 12 hours and had formed a nice, foamy head in the flask. I then split the starter into two sterilized (w/ Starsan) tupperware containers and chucked in the fridge.
Later today I checked on them and the yeast cake has a white/gray layer on top and a markedly darker/brown layer on bottom. I don't know if the bottom is dead yeast, or maybe one yeast strain is physically darker. Thanks for any input!
PS - I used the exact same method on a 1L starter for a Belgian yeast and it formed the normal, white/gray yeast cake on bottom.