There is also the possibility that Kindred is the doppelgänger of Harry Lyman, in other words his spiritual double (or, conversely, Harry Lyman could be the spiritual double of Kindred).

After all, a doppelgänger is a "kindred spirit".

(A) The doppelgänger motif: a staple of Gothic horror literature... and comics
https://en.wikipedia.org/wiki/Doppelgänger
https://www.britannica.com/art/doppelganger
https://www.thegothiclibrary.com/gothic-tropes-the-doppelganger/
https://www.theguardian.com/commentisfree/2011/nov/27/gothic-fiction-divided-selves
https://epublications.marquette.edu/gothic_doppelganger/
https://en.wikipedia.org/wiki/Siebenkäs
https://en.wikipedia.org/wiki/The_Devil's_Elixirs
https://en.wikipedia.org/wiki/William_Wilson_(short_story)
https://en.wikipedia.org/wiki/The_Double_(Dostoevsky_novel)
Doppelganger_(Spider-Man)_(Earth-616)_from_Amazing_Spider-Man_Vol_1_384.jpg

(B) Nick Spencer & doubles
https://marvel.fandom.com/wiki/Steven_Rogers_(Earth-61311)
https://marvel.fandom.com/wiki/Last_Son_of_Kraven_(Earth-616)
https://marvel.fandom.com/wiki/Mystique_(Item)
https://marvel.fandom.com/wiki/Peter_Parker_(Isotope_Genome_Accelerator_Duplicate)_(Earth-616)

(C) The Egyptian connection
According to Steve Ditko, Stan Lee initially wanted the Goblin to be an ancient mythological demon released from an Egyptian-like sarcophagus.
Kindred is a mummy protected by centipedes and, actually, there is a centipede god in Egyptian mythology. It is associated with Horus ("life"), Anubis ("death") and Osiris ("resurrection").
https://ancientegyptonline.co.uk/sepa/
Ancient Egyptians believed that a person has a "spiritual double", the Ka.
https://en.wikipedia.org/wiki/Ancient_Egyptian_conception_of_the_soul
https://www.historymuseum.ca/cmc/exhibitions/civil/egypt/egcr05e.html
https://www.britannica.com/topic/ka-Egyptian-religion