Jesus. Christ.
There was some event that went live on Lockjaw that shouldn't have gone live on Lockjaw that unlocked every expansion. That caused everything to go go crazy. People could level above 50, all of the drop tables were changed, all of the out of era merchants were present, Gukta was in Rathe Mountains, Defiant gear was dropping, etc. If, during that time period, you bought a bunch of spells that were out of era and stuck them in your guild bank after the rollback occurred you still had them in your guild bank. The shared bank information is stored differently than character inventory information. If you dumped a bunch of bonkers shit in your shared bank during the 5 or so minutes you had before the servers went down than when the rollback happened you had one set of gear on your character and then another set of gear in your bank.
There. Is everyone up to speed now? Is everyone exactly aware on how to duplicate items and currency each rollback?