Many applications involving complex networks, including public opinion guidance and control, viral marketing, and epidemic containment, require the identification of multiple influential nodes. An effective seed set should combine strong spreading ability with limited overlap in coverage. Methods based mainly on individual-node influence may select several seeds from the same densely connected region; this concentration limits the additional coverage of later selections. To address this problem, we propose a propagation-direction redundancy suppression (PDRS) algorithm that accounts for heterogeneity among a node's propagation directions. PDRS assigns each direction a weight based on the connectivity of the neighboring node and the redundancy indicated by common neighbors. The entropy of the normalized weight distribution defines an effective direction index that quantifies the effective number of low-redundancy directions supporting propagation. After selecting a seed, PDRS reduces each adjacent candidate's score according to the share of its directional weight assigned to directions that overlap the seed's local coverage. The candidate's local clustering coefficient adjusts the reduction. Subsequent seeds are therefore selected from less-covered regions. For directed networks, two-hop reachability quantifies subsequent spreading capacity, while local reciprocity adjusts the score reduction. We compare PDRS with 13 methods under the susceptible-infected-recovered (SIR) model on nine real-world undirected networks and nine real-world directed networks. Under these SIR settings, PDRS achieves the highest overall mean final infection proportion among the methods compared and reduces local coverage overlap among selected seeds. Ablation results show that the effective direction index changes the initial ranking, whereas the dynamic score update contributes more to the observed improvements in spreading performance and seed dispersion. PDRS therefore balances the spreading ability of individual seeds with the suppression of redundant coverage within the seed set.