I am wholeheartedly agreeing with you. I can actually go into Palborough Mines regularly and find a few people that are dual-boxing; one is real person, other is their 2nd account running a regular repeating pattern over & over in EXACT same motions, literally to near pixel by pixel, exact same run routes, exact same attack patterns. I've actually done /follow on it, aggro'ed the quadavs just before he could, and the 'bot would run off to next, constantly. I did this for near 15 minutes, and the 'bot didn't seem phased one bit and it kept on going and going like an Energizer Bunny. I have been farming all my own spheres too and working on it my own, but the 'bots are killing it for us that are legitimately farming.
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My response would be to make the spheres non-sellable, non-tradeable. Inter-characters on same account (mules) I can approve of as ok. Make them /ex. Either you use them or lose them, no more of this sell for gil and deprive others of it. Farm them, use them, make the shield, make the items from shield help, earn gil THAT way, not by making others fight over claiming mobs for these mats.
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There is one dual-boxing player I know that is legitimate; she is farming them for her own shield process and using one to kill and one to make spheres, but the other 3+ pairs (probably more) are just killing it for rest of us.