Why do I have two versions of my podcast on Spotify after changing hosts?

That’s a duplicate-listing issue, not something you need to solve by deleting random episodes. Spotify says that if two versions of a show appear, contact Spotify for Creators support and tell them which listing you want to keep. Include the link to both listings and your current RSS feed so they can keep the right version connected to it. They can usually preserve the listing with the most followers, but they can’t merge or transfer followers, analytics, or other data between the two. So before you contact them, double-check which one is the current show and which one has the audience you care about keeping.