It's clearly a typo - it was entered as "3/17/66" when 3/17/67 was meant. The show can't possibly be from any earlier than late '66.
I'm surprised the date actually got changed in deadlists, since it's been in dispute for some time & has been debated on deadlists recently; Latvala held that this show was actually 3/17/67. The update notes that the date's based on "information from Rob Eaton," so I would guess Eaton confirmed this?