From 2015-2016 I used to play an Australian combat surf server called Aus surf, as well as a variety of australian scoutzknivez servers.
They used to both have this plugin, whereby when only 1 player from each team remained, each played would be prompted to 1v1 with a scout, noscope only (scoping in was disabled) and there would be beacons displaying where each player was. Music would also play (I am looking for a specific song which used to play on these servers during the 1v1s).
From my research, the closest plugin I've found which has the same 1v1 prompt, as well as the same beacons effect and supported music was this old but popular plugin called KnifeFight -
https://forums.alliedmods.net/showthread.php?t=94572
From what I remember, the one with scouts was identical, besides it obviously being a scout noscope 1v1 rather then a knife 1v1.
If anybody knows any information, or has any leads it would be much appreciated!