dmfilipenko
duplicate abbr
"ADT", "AST", "BST", "CAST", "CDT", "CEDT", "CST", "EAST", "GDT", "JST", "KST", "MDT", "MST", "NST", "PDT", "SAST", "TST", "U", "VST", "WAST"
Yes, there are duplicate abbr's in multiple objects. Go to timezones.json and ctrl+f CDT, there are two objects containing same abbr values and same for others too.
Some of these are related to the offsets being wrong in the other bug where the offsets are wrong, because the file was generated using the state of things while DST/Summer Hours was on in the Northern Hemisphere.
E.g., MDT - 2 of those are "MDT" for "Mountain Daylight Time" (1 for the US/Canada, 1 for Mexico which kept the pre-2005 dates that Europe is generally also using). Both should have been MST.
The abbreviation duplicates in general, I'm not sure if they can be resolved. Both are Mountain Standard Time in the winter, Mountain Daylight Time in the summer, but on different dates. "Complicated" :)
Oh! These timezone things have always been complex. I resolved the duplication issue, by creating a single object for all duplicate abbreviation. In short, I edited the JSON. If you need that , let me know... :-)