Question- Mystery Plug

[johnny knuckles]

Got my block back from the machine shop. Started re-assembling it. Back by rear main seal I noticed something wierd in one of the holes. I was a some sort of plug that was in the hole sideways. I can't recall if it is supposed to be there or not. (I know it doesn't go in sideways if it does though). It was in the passage that goes between the oil filter to the main. There was another plug below it that looked good. I'm just not sure if there is suppose to be one above the plug that is deep down in there.

Anyone know? Here's some pictures to show what I'm talking about.