Megablooms are when two or more flowers fuse together to create a single bloom from which larger fruit can form. As they are independent flowers, they have to be individually pollinated and the resulting fruit will normally be misshapen and may experience “catfacing” or “zippering”.
Our experience is that megablooms tend to occur on the early flowers of beefsteak tomatoes which tends to support the idea that megablooms are due to plant stress caused by cool temperatures or temperature variation.
Some people remove these blooms from their plants but we can’t see any reason to do so. Yes, catfaced fruit need peeling to get rid of deformities but to be honest that’s not a problem and if you’re trying to grow large fruit, its the only answer.