When a duplicate post like this comes up, I usually flag it. Does anyone else do this?

It really fragments discussion having duplicate posts on the main page since people usually just comment on the first one they see.

I also noticed that the only difference in the URLs between the two was a trailing slash. Shouldn't that be included in the dupe detection? Probably the most frequent and easiest to catch cause.

Yeah. I thought HN would catch trailing slashes.