In 这个跟那个不(是)一样 and 我们不(是)一样, is 是 totally redundant? 这个跟那个不一样。   From a native online teacher.

这个跟那个不是一样。  If I formed it myself.

我们不是一样。  If I formed it myself.

我们不一样。  If I followed the similarity of 1 above.


I know the first one got to be correct.  what about the rest?
Edited: I just happened to use the negative  不 in those sentences.  But my question also applied to without the 不.
'不一样' (is not the same) is a set phrase, functions the same as '是不一样的' therefore 是 is redundant in '不是一样'
Either '这个跟那个不一样' or '这个跟那个是不一样的', but not '这个跟那个不是一样'