I'm not following some of this. If someone added a web cover and there is actually an officially released version then clearly the web cover must be deleted and the officially released version must be added.
In my opinion we have one flaw in our system with detecting and displaying Web Covers. Let's say I was going to add a new released performance. If the artist already had a released performance on SHS I would get a pop up warning indicating there was already one on SHS asking me are you sure you want to do this (and there may be a good reason for adding it if one is a vocal vs instrumental or medley part). However if an artist already has a web cover on SHS and I went to add a released performance, I wouldn't get that pop up letting me know we already had one on SHS. I've stumbled upon this before because the video I chose to upload had already been used and lo and behold it was used on a web cover. So my recommendation is the warning pop up indicating there is already a performance on SHS by that Artist should also detect Web Covers so we don't have both versions on SHS and know to delete the Web Cover. Frankly I'm suprised it doesn't already do this, but it definitely doesn't as I just tested it myself and didn't receive a pop up warning.