InnoDB automatically appends fields that you have as your pk to all secondary indexes.

The only exception is when you yourself specify some or all of the primary key fields in the secondary index, in any order - it does account for that and avoids duplicating them again. So no, it is not redundant, in fact it is preferred so you can control the order of indexed columns (should it be distinct from pk's) and to make RDBMS more aware of the actual capacities of the index.

Relevant blog post: https://lefred.be/content/mysql-innodb-primary-key-always-included-in-secondary-indexes-as-the-right-most-columns-or-not/