Or HaChaim on Genesis 42:11/אור החיים על בראשית מ״ב:י״א

1 כלנו בני איש אחד, "we are all the sons of one man." There is no reason to suspect us of being spies. Spies are always from different branches of a community. Moses sent out spies from all the twelve tribes; even the two spies Joshua despatched were not sons of the same man. It is in the nature of things that spies should be representative of the people on whose behalf they spy. It would not make sense to appoint ten members of the same family as spies. They added: כנים אנחנו, "we are honest men," meaning that after we have identified ourselves it should be obvious that we are honest. Spies would never identify themselves voluntarily.

2לא היו עבריך מרגלים, "your servants have never been spies." They chose the past tense to indicate that they had not even been spies before they had been identified. Naturally, now, that they were known, they could not be spies even if they wanted to.