I think the ideal is for someone to have a very deep knowledge of two different fields, or areas of interest, while also having broad general knowledge. This gives people an idea both of how deep human knowledge runs, and how wide. With only one area of interest, some people might come away with the idea that one area is somehow unique and different. With two, there's more reason to conclude that other areas are just as deep.

You can also try to counter your bias by always remembering the adage:

"Specialists will tend to underestimate how well a Generalist can specialize, when they choose to specialize. Generalists will tend to underestimate how deep any given specialty goes."

I'll have to remember that one. In a way, I'm advocating for everyone to be at least two kinds of specialist and generalist at the same time.