Case:

Here A and B are simulators and the numeric values are time.

Initial array:
[ A:0, A:1, A:2, B:0, B:1 ]

Index:
  0    1    2    3    4

Pass 1:
i = 0
   v
[ A:0, A:1, A:2, B:0, B:1 ]
  ^    ^
  |    |
  |    +-- compare with A:1 -> same simulator kind as A:0
  +------- current item A:0

Action:
- remove A:1

Array becomes:
[ A:0, A:2, B:0, B:1 ]

New index layout:
  0    1    2    3

Problem in old logic:
- after removal, loop still increments i
- so i becomes 1

Pass 2:
i = 1
        v
[ A:0, A:2, B:0, B:1 ]
  0    1    2    3

Now we are at:
       ^
       |
       +-- A:2

So the comparison is now effectively:
A:2 vs B:0

That is fine, but:

[ A:0, A:2, B:0, B:1 ]
  ^    ^
  |    |
  |    +-- still another A remains
  +------- original A still present

So we skipped re-checking index 0 against the new shifted value A:2.