I know GM Ahn changed over to Kukkiwon style from Tang Soo Do back in the 70's, but he still received his 9th Dan from Taekwondo Moodukkwan, in addition to Kukkiwon.
I think GM LEE Chong Woo promoted GM Ahn to Kukkiwon 9th Dan, back when all the seniors were getting that around 1990 or so.