Regular and whole wheat. If a woman kneads two doughs from wheat flour, each less than the minimum amount, and she does not want them to get mixed together [e.g., one is regular wheat and the other is whole wheat, or one is regular wheat and the other is sourdough], they do not join to meet the minimum shiur (שו"ע שכ"ו ס"א ). Accordingly, if each one is less than 1.2 kg, hafrasha is not done; if each is less than 2.25 kg, hafrasha is done for each dough separately without a bracha.
Kokosh cake, challos. The same is true if one is making kokosh cakes along with challos. If the doughs are somewhat different and care is taken not to mix all the dough together, even if their recipes are similar (שו"ת אבני צדק מהדורת תשנ"ג בהוספות סי' ו' ) they do not join to meet the minimum shiur (לקט העומר פ"ו ס"ט ובהערה ).
Chocolate and cinnamon babka. If the two doughs are identical, just she is planning to fill one with chocolate and the other with cinnamon, they join to meet the minimum shiur (שם ובשו"ת שבט הקהתי ח"ד סי' ער"ה ).
