The measured vacuum level will change depending on where you measure the vacuum. If you measure inside the wiped film column, you will measure a much greater pressure due to the volatile components in the vacuum. As those volatile components diffuse through the vacuum system, they encounter a series of condensers which act to condense those vapors. Vacuum sensors on the downstream side of the condenser often measure much lower vacuum.
Various manufacturers place vacuum sensors in different locations and successfully produce distillate.