Give both The Skarners SEPERATE crystal shrines
Playing Skarner vs Skarner has to be the biggest pain in the ass of all time in this. With the rework A skarner will always highly prioritize capturing the shrines. So what happens when 2 Skarners share the same shrines? They get captured and recaptured every 10 seconds by both skarners one after another. Sometimes a more fed skarner may even camp the shrines to then jump on the less fed skarner when he arrives there to easily kill him using the buffs.
Both teams shrines should still cover dragon and their own buffs (OWN buffs, not necessarily the enemy buffs), but at slightly different locations.
This would also fix your issue with two skarners removing each others shrines. In fact two skarners sharing the same shrines would almost be impossible due to different skins having different textured shrines.