The Mekhilta addresses a precise scenario: what happens when a master knocks out two of his bondservant's teeth — or blinds both eyes — simultaneously, in a single blow? The ruling is striking: the bondservant goes free but receives no additional injury payment. The freedom itself is the compensation.
The logic derives from the Torah's language: "an eye for an eye, a tooth for a tooth." One eye grants freedom. One tooth grants freedom. But when two are lost in a single event, the freedom triggered by the first loss absorbs the compensation that would have been owed for the second. You cannot be freed twice.
However, if the master knocked out one tooth and then, in a separate incident, knocked out a second tooth, the legal result is different. The bondservant goes free for the first tooth — that right is irrevocable. For the second tooth, since he is already a free person at that point, he receives monetary compensation for the injury, as any free person would. The text says "in lieu of his eye" — the freedom is granted in exchange for one loss, and subsequent injuries are compensated separately.
The distinction between simultaneous and sequential injuries creates an intricate legal framework. Timing matters. One blow with two consequences produces one remedy. Two blows with two consequences produce two separate remedies. The Mekhilta treats each act of violence as an independent legal event with its own consequences.