For some time I had a CV1931 on the website, the example being a 6H6 metal double diode, though not 6H6 marked. Today I got a glass CV1931, also marked 6H6GT. I never checked before but the metal one is clearly incorrectly marked.
The CV Register has three CVs in a series: CV1929 / 6H6G, CV1930 / 6H6 and CV1931 / 6H6GT. This makes sense.
For now I’ve left the page as-was but added the glass valve.