No they didn't change their names. They may have been omitted from the list by oversight. They don't appear on the later list either.
OK, so another theory. Maybe they didn't donate 50 BTC but were gifted the VIP status because of their contribution to Bitcoin and the forum.
Yeah - I did think that could have been the case. Especially with Hal being a bitcoin icon.
Mark Karpeles (MtGox) provided the hosting and provided technical services to bitcointalk from 2011 onwards.
https://bitcointalk.org/index.php?topic=42572.0 so probably provided services well in excess of the 2011 50BTC value.