I don't have Max right now to test it but it should work.
Instead Conditional Node that has a Segment Pole Counter place Sequence Node and connects Transform nodes in the order you need:
lampost/mid post/lampost/mid post
Then set the Counters in the Sequence properties 1/1/1/9
Connect this Sequence node to the Evenly Connector of the Generator (I think it is named as Linear_2)
Keep in mind this will distribute Sequence along all spline following Evenly distribution so it is possible that positions of the Lampost will not be on some position you presume to be because of the corners.
For that more complex distribution, I assume we should introduce some Mat ID limits