On Micro.blog you can follow other people with Micro.blog accounts. But you can also follow folks on Mastodon (ActivityPub) and websites (as long as they publish a web feed). So most of us have more than one representation on Micro.blog. You, for example, have at least four:
These feeds might be identical content-wise, depending on how you set up our web presence with crossposting, etc.
Most of the discovery section is handled manually by @jean and @manton. The duplicate entries are probably caused by human hands, adding the same content from two different accounts to the discovery feed.