1894M 22 mag - Too many holes?

[bowboy]

I just picked up an 1894M. I question if it has had additional holes added on the reciever, or if these are all original.

There are five holes in the top of the reciever, all with plug screws. I don't recall seeing another Marlin lever action with more than three holes for scope mounting.

It also has a hole on the left side of the reciever, right at the breech end of the barrel. I assume if the hole is supposed to be there, it should have something in it. Any help would be appreciated.