Background: What is redundancy? While most studies confirm that redundancy is harmful to learning, there are two theoretical approaches to redundancy. The first understands redundancy as a contentual overlap that puts demand on the limited cognitive capacities of the learner. The second understands redundancy as an ineffective combination of sources leading to an overload of the limited working memory modalities. Aims: Since these theoretical differences are rarely acknowledged in operation, this study proposes a classification of two distinct types of redundancy to compare these experimentally to investigate their possible main and interaction effects. The first type, content redundancy, is concerned with the contentual overlap of information. The second type, modal redundancy, is concerned with the modalities in which the information is displayed. Methods: We used these two types of redundancy as factors in a 2 × 2 within-subject design, in which we experimentally compared their effects. Sample: University students (N = 46) learned from specifically designed domain-general material which aimed to observe redundancy effects without interference from confounding variables. Results: The results show that content redundancy increases learning outcomes and decreases cognitive load, while modal redundancy decreases learning outcomes and increases cognitive load. Conclusion: On the theoretical level, these findings confirm the usefulness to distinguish content redundancy from modal redundancy. On the practical level, the empirical findings of the different effects of the two types of redundancy provide educators with important insights that can improve the design of multimedia learning materials.