Use polarities when pairing
If you do pair testing on a regular basis, try this and see what happens. Take a look at the list of different test polarities and try using them when you pair. Explicitly call out in advance, "I'll approach this session from this side of the polarity, you approach it from the other." Some polarities that work particularly well for this include: doing vs. describing; or doing vs. thinking; 0r data gathering vs. data analysis; or working with the product vs. reading about the product.