This doesn't occur in NL because a special rule exists to avoid it:
Suppose a builder places a brick while standing at point X, and facing to the right. We will call this brick Y.
After placing this brick, a blocker is placed such that the builder turns around. (Alternatively, a cloner is used to create a duplicate lemming which is facing the other direction; the rule applies in both cases.)
In such a circumstance, a new brick is placed, equivalent to what the builder would place while standing at point X if he were facing to the left. Brick Y also continues to exist.
The rule is also applied to Platformers (and I think Stackers, though I'm not 100% sure on this one; at any rate Stackers only have a one frame window in which this could apply, unlike Builders and Platformers which have a few frames of space to do this), but is far less visible due to that the brick would most often be overlapping an existing one. However, it can be observed at least with Platformers when the rule is triggered due to Cloner usage during placement of the first step. In fact, if I'm not mistaken, in newer builds Nepster has made such a rule apply to destructive skills as well.