The spelling of the word "Proproctor" is quite unique and can be explained using the International Phonetic Alphabet (IPA) transcription. The word is pronounced as /prəʊˈprɒktə/. In this transcription, the symbol /ə/ represents the schwa sound, which is a neutral vowel sound. The letter combination "pro" is pronounced as "proh" with a long O sound. The word "proctor" means a supervisor or invigilator, and the prefix "pro-" means before or in advance. Therefore, a "proproctor" can be interpreted as an assistant supervisor or a person who supervises the supervisor.
In Eng. universities, an assistant proctor.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.