I picked a ‘Polish dwarf’ tomato the other day that looks like two fruits that grew together.
It appears that this happens when multiple blossoms fuse together into what is known as a “megabloom”. It seems that this usually happens early in the season, probably during a cold spell. See more in these links:
The scar on the top left of the tomato fruit is due to cracking, which happens when the skin can’t grow as fast as the inside of the tomato. This can be caused by temperature or soil moisture fluctuations, both of which we’ve experienced in the past month.
See more about cracking, and many more tomato fruit problems, at this Missouri Botanical Garden webpage.