This study assessed the results from the parallel application of two alternate personality models, the Zuckerman-Kuhlman trait model and Bond's Defense Styles, in a sample of 268 Greek medical students (172 women, M age = 22.0 yr., SD = 1.1; 95 men, M age = 22.3 yr., SD = 1.2) in relation to psychopathological symptoms, so as to clarify whether this practice yielded accurate results while avoiding shared variance. Data from both models are cross-checked with canonical correlation analysis to validate whether there was significant conceptual overlap between them that would mean that their parallel use is an ineffective research practice. Following this analysis, factors from both models are utilized to predict variance in sample psychopathology, so as to compare their relative usefulness. Results indicated that the two models did not share a significant amount of variance, while a combination of personality aspects from both models, including Impulsive Sensation-Seeking, Neuroticism-Anxiety, Aggression-Hostility, and Sociability traits and Maladaptive Action, Image Distorting, and Adaptive Action defense styles, predicted high variance in psychopathology symptoms.