Thank you for sending a sample. Upon checking, I was able to verify that Breakfast and Appetizer both use the MenuItemID field. This explains why the value from the first drop down is carried over to the next drop down. Also, when you insert an entry for the first drop down, the second drop down will also have an inserted field, so it's sort of a mirror image. I would recommend having another group specifically for the Appetizer section. Something like this sample image below:
A is the Breakfast group and B is the Appetizer group.

Let us know if this helps.