Both just Esty Cents. My grandson has a handful of zinc cents he "shined-up" on the sidewalk at school that look like your 1992 and 2008. Keep researching and searching.
Do you know about the planchet that is struck to make the cent? Since the cutover during 1982, the cent is made from a zinc core (one that has a tiny bit of copper in it so the plating adheres better) plated with a thin coating of pure copper (8 microns - a human hair ranges from 25 to 180 microns). Under the extreme stress of the strike, the plating sometimes splits. This shows as a silvery (exposed zinc) halo on some of the raised devices (often the letters). It's sometimes called split plating doubling, but it's not doubling. When the struck planchet (now a coin) leaves the mint, you have raised letters that are mostly zinc, with that tiny amount of copper on top. Rub it on something abrasive (600 grit emery paper is a good choice) and you will see how easy it is to expose the silvery part. Rub the edge on that abrasive paper at a slight angle and you'll see how easy it is to create that sloped silvery bit. Rub the whole cent flatly and you will see how easy it is to create that flat relief bust of Abe Lincoln. Go ahead, try it. The mint makes billions of cents each year and they won't miss the one or two that it takes to convince you this is damage. Now, etiquette... when you come here and ask questions, there are dozens of people willing to help. If you ask intelligent follow-on questions, you'll get replies. However, if your tone is combative or argumentative, many people here just drop the thread or put you on ignore. You have people here who have been collecting error coins for 30+ years. You have people here who have been dealers of error coins for 30+ years. You have people here who write the columns about error coins you read in magazines. You have people here who publish the online magazine (mint error news) you should be reading about error coins. You have people here who maintain the canonical website for coin errors (error-ref.com). I'm sure you didn't mean anything, but remember, a message board even with smilies and such doesn't handle the complexities of tone you get face-to-face. So tone it down a bit. If you really want to LEARN about error coins, you really don't want those people to ignore you.
Sorry If I offended anyone in the board regarding their expert opinions. I know you guys have a lot of experience than I do and more knowledge regarding errors. It was just hard to believe from my side with no experience to understand. I do not mean to come strong and I do appreciate all the people in here who guides and teaches me to the right places. I just really want to understand how and whys. Now I understand that the coin is a Dryer coin. It had very similarities in the pictures. It was very hard for me to believe that this was filed down or grinded down. That is why I was just asking how could a coin end up like this coin shown in the picture. As you can see, how can the inside of the "B" be effected as well.
Your question about the grayish color inside the loop of the B, it likely is copper oxide. There is 2.5% copper mixed with the zinc and heat from the grinding matrix can oxidize both metals, zinc is a white oxide while copper oxide is deep black . My thought is that the part in the photo above , the letters rising higher than the surface would have more heat generated by the longer exposure to the grinding and the much darker copper oxide buildup whereas the inside is mixed but less heat and thus grayish. Theory, just theory/ Jim