In the Dixon resultant elimination method, the problem of removing extraneous factors during its construction is very difficult. The first two authors of this paper have proven the existence of at least three types of extraneous factors in Dixon resultants. However, the proof of existence of the first two types is extremely complex. In this paper, we describe a simplified proof based on the generation mechanism of these two types of factors. In addition, we observed that different deduction processes would probably result in different extraneous factors.