Adding List Element if Second part of the List Elements are the Same

[quest_]

Hello,

I have this list

newlist = [[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]],(1.57, 1.57, 0)],
[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]], (0, 1.57, 0)],
[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]], (0, 1.57, 1.57)],
[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]], (0, 0, 0)],
[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]], (0, 1.57, 0)]]]]

Here I want to compare second part of the list (this part: (1.57, 1.57, 0), (1.57, 1.57, 0), (1.57, 1.57, 1.57).. ) and if the second parts of the list are same? I want to add them together. For instance the list which I wrote above we have 2 times (0, 1.57, 0) so the new list should be like that:
newlist2 = [[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]],(1.57, 1.57, 0)],
[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1],[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]]], (0, 1.57, 0), (0, 1.57, 0)# here instead of adding(0, 1.57, 0) again we can just put 2 for remembering we had 2 times (0, 1.57, 0)]
[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]], (0, 1.57, 1.57)],
[[[0, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0], [1, 0, 1], [1, 1, 1]], (0, 0, 0)]]]

How can I do that in an efficient way
Thanks for helps..