Yes. That's why we ended up getting the TrailGator instead. But the trailgator is definitely not compatible with our rear seat -- it needs an empty back rack. You could do a front seat + trailgator. But this tandem coupling thing looks a lot more stable, and as we bike more and more, or if we add another kid and limit our options further, it seems like it might be a reasonable investment.
If your other choice is buying a family tandem (like the
Onderwater family tandem, which is $3000) the tandem coupler starts to look downright reasonable.