Let me just address this notion of "I have to pay for something twice". No sir, you don't. The DAZ Legacy Carousel is a support item for the Poser 4 horse, much like you would buy clothing items for a specific figure. When you buy clothing for Don, Judy, Jessi or James, you're not entitled to the figure if you don't already own it. The same applies in this instance.

There are still two places for Legacy content if you have a valid serial number:

For the Poser 4 Horse you would need the Poser 6 Legacy Content available here:
http://poser.smithmicro.com/content_update.html

The same downloads are also still available here:
http://support.contentparadise.com/updates/index.html