those magical moving hyphens (lawrence-hilton jacobs edition)

Anyone remember Welcome Back Kotter? It was a crappy 1970's sitcom that was really popular but hasn't aged well. It's probably best remembered as the vehicle that gave us John Travolta. Here's the theme music:

While you're watching that, please notice the credit for the character Washington. It's Lawrence-Hilton Jacobs. With a hyphenated first name. Like the country singer, Mary-Chapin Carpenter.

Yet now, if you look for Jacobs on the intertubes, he is listed everywhere* as "Lawrence Hilton-Jacobs." With a hyphenated last name. The first time I noticed that -- I was looking him up on Wikipedia -- I thought I must be misremembering. But, no...finding the video of the old WBK credits told me that I remembered correctly.

In fact, the Wikipedia entry lists his parents as Hilton and Clothilda Jacobs. So it makes sense that his last name is Jacobs. Not Hilton-Jacaobs. Further, since his father's first name is Hilton, it's easy to surmise that his parents named him Lawrence-Hilton, partly after his father.

So when did the hyphen move and why? Is the whole intertube community suffering from memory loss? Or did he actually change his name? And if the latter, then why is that not listed on his Wikipedia page?

These are things I need to know. Also, why did the hyphen disappear Mary-Chapin Carpenter's name?

*Well, almost everywhere. In putting together this post I looked him up on IMDB and found that, there, the hyphen is in his first name.