I haven't run across this style of connecting (?) to a screw terminal before, so I wonder if it was an approved method (ever, anywhere, but I found this in British Columbia Canada, installed ca. 1997).
This is an "Eagle" receptacle, made in Canada, and has CSA (but not UL) markings. It has rear push-in terminals.
This technique seems to provide a fair bite on the wire, but the contact area looks to be pretty small.
There doesn't seem to be any other obvious reason for the hole, but perhaps it was intended to assist in wrapping the wire around the screw? (it works quite well for that)
Any wisdom appreciated...