Scientific “jangle” occurs when two nominally different measures assess the same construct. Such “jangle” can waste resources and slow scientific progress. There is currently substantial debate surrounding the distinctiveness of the “dark factor” (D) and Agreeableness-Antagonism (A-A) as important personality constructs. The current preregistered study explores the similarity of D and A-A using an interpersonal perspective. By reanalyzing previously published data collected from a large student sample (N = 516) using the structural summary method, the study compared these two constructs with regard to their interpersonal content. Results indicated that D and A-A had identical interpersonal profiles at the total score level. Although there was variation among A-A facets, the D total score fell solidly in the middle of the facets. Similarly, there was no evidence of differences in interpersonal content at the item level. The current study suggests that D and A-A are fungible in terms of interpersonal space, at least as measured via self-report questionnaires.