Shorter than a Split Second!
APL (Dyalog 14) (31)

{1↓¨(1,(⍳⍴⍵)∊2⍳⍨¨↓+\∘.=⍨⍵)⊂0,⍵}


This is a function that takes an array and returns a nested array.

Test:

      +V← {1↓¨(1,(⍳⍴⍵)∊2⍳⍨¨↓+\∘.=⍨⍵)⊂0,⍵} 2 1 1 2 3 2 2 4 5 6 7 3 7 0 5
┌───┬┬─────────────┬┬─┬┐
│2 1││3 2 2 4 5 6 7││0││
└───┴┴─────────────┴┴─┴┘
      ⍝ this return value is a real nested array:
      ⎕←'Length: ',⍴V ⋄ (⍳⍴V){⎕←'Array #',⍺,': (', ⍵, ')'}¨V 
Length:  6
Array # 1 : ( 2 1 )
Array # 2 : ()
Array # 3 : ( 3 2 2 4 5 6 7 )
Array # 4 : ()
Array # 5 : ( 0 )
Array # 6 : ()


Explanation:


0,⍵: Add a 0 to the front of ⍵, for easier processing. (It does not count as an occurrence.)
(...)⊂: Split the array according to the given bitmask. A new group starts at each 1 in the bitmask.

+\∘.=⍨⍵: for each value in (the original) ⍵, find all occurrences in ⍵. Then make a running sum for each value, giving a square matrix showing for each position in ⍵ how many of each value have already occurred.
↓: Split the matrix by its rows, giving for each value an array showing the amount of times it has occurred by each position.
2⍳⍨¨: In each of these arrays, find the index of the first 2.
(⍳⍴⍵)∊: For each possible index into ⍵, see if it is contained in the list of indices of second occurrences. (These start each group, except the first one.)
1,: Add an 1 to the front, marking the start of the first group.

1↓¨: Remove the first element from each group. (These are the added 0, and the second occurrence of each value.)