Pretty sure there will be a mechanism preventing such things. Maybe not 2 or 3 wallets on 3 different PC’s (nearly impossible anyway). But i doubt it would make sense for example having someone with 1000 wallets and 1000 different IP’s…
I guess we will soon see it how different projects try to solve this problem as several coins are working on exactly such POS (Proof of Stake) and POC (Proof of Credit)…