We had a similar speed booklet (recently replaced with the same information on a single card). Once we have calculated a V1 and Vr for aircraft weight, we then have to check the performance manual for the particular runway, temperature, surface conditions, wind and anti-ice status to see if V1 is reduced below this figure.
Could your company be reducing your MTOW deliberately to give a bigger safety margin? The despatchers could be figuring a Max V1 for conditions on the day, then using this max V1 as the basis for limiting TOW.
Please note: the above is only my guess.