multiple admissions of liability

Colorado.
I have received three admissions of liability from the insurance company on my workers compensation case over a three year period. Each appears to be the same except for the date the admission is created and the cumulative amount paid. Does the second negate the first or the third the second for purposes of when their liability started? Thanks

I suggest you contact the WC carrier and ask them to explain why they're sending these letters and what they mean.