Can I only select a single skill?

Uber noob question here, but in the rows of skill upgrades, it will select the latest I upgade. Does this mean I can only select a single skill upgrade per row? In the image below for example it's useless to train both of the skill upgrades since it only picks the latest I upgrade?

https://preview.redd.it/zk7lbsnhotng1.png?width=433&format=png&auto=webp&s=f76ac4ddf327d4ae32ae617ac790ea8d77779e88