@zandertrek There exists both the option to upload from users local file system and/or provide a link to something external.
The copy/paste/drag/drop from local filesystem uses the "Upload Image" feature/function while the "Picture" icon employs the link feature. So both are complimentary.
Given the above: No, the icons are not redundant, but could perhaps use better mouse hover labels?
Here is an example resulting from "Upload image" from my local file system:
Here is an example using a link via "Picture", wh/requires a link and optional "alt text":
Clear as mud? Hovering over the images above may help clarify.
Edit: Need to clarify the above a bit: Seems the copy/paste image link also automagically employs the "Picture" function, wh/is same as "Link" chain only it prepends an exclamation point (!) to denote markdown image link.