Upvote for the research efforts & may be true.
However, seems the address you've found is Linden Blvd, but the original poster is Linden Ave. I'm sure if this was a lost keys poster by someone who lives there would know that.
Secondly, says in the poster "front and back house keys" but its an apartment block (posting says #1a), not a house (ok they might casually refer their own apartment as a house at a push), plus there's also no visible back door on street view. May be hidden but why would someone list exactly what each key fits & not describe what they look like instead?
Some people might make some of the listed mistakes, but not all.
This is either a prank on someone who they want to get burgled or just for laughs. Otherwise its a perfect list of exactly what not to do when you loose your keys.
