Caveat: I'm not sure there's substantial philosophical literature on the question of evaluating philosophical theories for uniqueness. After looking on PhilPapers, I did find a few papers that seem to be related. From the abstract of Common minds, uncommon thoughts: a philosophical anthropological investigation of uniquely human creative behavior, with an emphasis on artistic ability, religious reflection, and scientific study:
The aim of this dissertation is to create a naturalistic philosophical picture of creative capacities that are specific to our species, focusing on artistic ability, religious reflection, and scientific study. By integrating data from diverse domains (evolutionary and developmental psychology, cognitive anthropology and archeology, neuroscience) within a philosophical anthropological framework, I have presented a cognitive and evolutionary approach to the question of why humans, but not other animals engage in such activities. Through an application of cognitive and evolutionary perspectives to the study of these behaviors, I have sought to provide a more solid footing for philosophical anthropological discussions of uniquely human behavior. In particular, I have argued that art, religion and science, which are usually seen as achievements that are quite remote from ordinary modes of reasoning, are subserved by evolved cognitive processes that serve functions in everyday cognitive tasks, that arise early and spontaneously in cognitive development, that are shared cross-culturally, and that have evolved in response to selective pressures in our ancestral past. These mundane cognitive processes provide a measuring rod with which we can assess a diversity of cultural phenomena; they form a unified explanatory framework to approach human culture. I have argued that we can explain uncommon thoughts (exceptional human achievements, such as art, religion and science) in terms of interactions between common minds (ordinary human minds that share their knowledge through cultural transmission). This dissertation is subdivided into four parts. Part I outlines the problem of human uniqueness, examining theories on how humans conceptualize the world, and what their mental tool box looks like. Part II discusses the evolutionary and cognitive origins of human artistic behavior. Part III focuses on the cognitive science of religion, especially on how it can be applied to the reasoning of theologians and philosophers of religion. Part IV considers the cognitive basis of scientific practice.
There doesn't seem to be any mention of methods for comparative analysis. Generally, in the Anglo-American tradition, philosophical analysis hinges largely on linguistic and conceptual analysis.
So, this high-level question has a few points to be addressed, but is certainly a question that is relevant in metaphilosophy because it asks a very fundamental question about the nature of how philosophy is done and what it is. Briefly, anyone can do philosophy if philosophy is seen as a simple effort of organizing concepts, using language, and organizing first principles for logical reasoning. According to the theories of some social philosophers all people take their cue from society for this activity at first; this emphasis on knowledge coming from society is known as social constructionism since people use the ideas and language of their society. At a certain point, when philosophical thinkers continue to pursue organized thinking, they realize it's easier not to reinvent the wheel and begin looking through historical and contemporary literature to find ways to contribute new ideas. But some do not. This is called heterodoxy and there's no limit to either idiosyncratic language use or conceptual schemas involved. Anybody can create a highly original philosophy. That being said, it's not really a branch of philosophy (academic discipline) unless there is a community organized around it. Occasionally, philosophical heterdoxy wins over enough thinkers and becomes the orthodoxy. This has become known as a paradigm shift after the work of Thomas Kuhn. However, it's rare for a branch to occur outside of academia, but like Ayn Rand's Objectivism has shown, it is possible. Ultimately, philosophy and all language use is a social activity, and like all language-games, there's not a lot of motivation to play the "game" without other players, particularly those who share the passion and skill. Even the brightest thinkers, if extremely idiosyncratic and heterodoxical simply tend to be ignored, and so their thinking doesn't become a branch.