Software development teams where everyone is alike, while comfortable, are not effective. Teams need to bring together a variety of skills, attitudes, and perspectives to see problems and pitfalls, to think of multiple ways to solve problems, and to implement the solutions. Teams need diversity.
Conflict is the inevitable companion of diversity. Not conflict in the "we hate each other and we just can't make progress" sense, but in the "there are two ways to solve this" sense. How do you choose?
Two ideas about a design present an opportunity, not a problem. The principle of diversity suggests that the programmers should work together on the problem and both opinions should be valued.
What if the team isn't good at conflict? Every team has conflict. The question is whether they resolve it productively. Respecting others and maintaining myself smooths communication in times of stress.
Diversity is expressed in the practice of Whole Team, where you bring together on the team people with a variety of skills and perspectives. The various planning cycles encourage people with different perspectives to interact with the goal of creating the most valuable software possible in the time available.