There many that are! An interesting question is if increased competition (from the same competitors) comes at the hand of government regulation. Let's say for p

There many that are! An interesting question is if increased competition (from the same competitors) comes at the hand of government regulation. Let's say for product X there are competitors A and B. They're not really actively competing, and in fact, have divided the market up between them. Then along comes the government, and says "Hey you two (John Deere and Caterpillar, or Apple and Google), you've formed a duopoly", and pushes some regulation (say, right to repair, or 3rd party app stores) on them.