Hello evzntv,
Ok, so EVERYTHING you said was CORRECT - BUT, this is what's been happening on my end, and I am not lying, I 100% understand lying will NOT help me get unbanned.
So first off, around 2-3 months ago this WAS my YT channel, but I really wasn't feeling my username was catchy, so I created a new id for myself: Dr_MineStein. I asked my brother if he wanted to take this old one (i.e., SkullDude101), and he took it, and he always wanted to start his own channel and I said here take this one. If you take a look at the latest content he's making stuff like Youtuber steveee. I'm really busy with school so I'm not really free to make videos, but he is, and 12 subs already is a good start.
As for the SkullDude101 user logging in first, you are correct. He was playing on another server with the SkullDude101 account and came directly to Sentinel. Then he thought "why use my alt, rather best to use my DaDiamondHeist account". According to him, he did not register in the username of SkullDude101 (that's up to you to verify). So actually my ORIGINAL statement "Turns out he tried to login after getting his 'DaDiamondHeist' account banned to see if it works lol." is FALSE, and that lil rascal didn't properly explain it to me.
And as for me changing my forum name, you are correct, I did it only on May 10. Why? You see, like i said before, I gave my SkullDude101 channel to my brother, so lately whenever I come across a site with myself registered as SkullDude101, I change it to Dr_MineStein or delete it, so my brother and I don't share like an internet identity. So I transferred everything, from the Gmail and Youtube and everything associated with that SkullDude101 ID to my brother. I had registered on May 10 with the email (i will not reveal it here) linked to SkullDude101 since then it was kinda unused. I had not come to sentinel at all since I got my appeal rejected, but after I came here to re-appeal at Sentinel, I immediately changed it to Dr_MineStein because that is my ID now, and didn't want to link this forum in my brother's name.
In case you are puzzled on how my brother joined the server AND me appealing/changing the username on the SAME day, well that's because I just got reminded to re-appeal when my brother asked me which server to play on.
Apologize for the big post, but whatever I'm stating here is true, and I want to be as clear as possible to you guys.