Every single advertiser is about to drop Twitter in the next 48 hours. Person creates fake Nintendo Twitter account, pays $8, gets verified immediately and within 2 hours, all their sh*posts go viral. Real Nintendo account gets spammed with complaints.
Yes and no, it depends whether you mean verified as in "Twitter verified" or verified as in "the journalist verified this is the genuine person".
Their job is to verify who it is that they're quoting. Having a blue tick (then and now) doesn't guarantee that the twitter account is genuine, but there are other ways to check this stuff.
Or even if it was authentic, there's no way even back then to be sure if it was the person really tweeting. (ie like the Ted Cruz controversy with the p*rn account)
If it's someone famous who hasn't "verified" themselves OR someone who says they are a certain famous person who wasn't previously on Twitter, then it would be best to contact their PR rep going forward to be really 100% sure.
It could be that there are really two people with the same name. Take Chris Evans, who played Captain America and also Chris Evans, who was a host of Top Gear.