Different spellings of Hjartdal?

[gj04322]

My father's ancestors emigrated to the United States from Telemark, Norway.
I have several municipality or parish citations using the following names:
Heddal, Hitterdal, Hitterdals, Hjertdals. I also have one map of Telemark municipalities, which was originally posted on the Johan Borgos website. On it there is only one municipality with a similar spelling: Hjartdal. Could this multiplicity of names be alternative
spellings of the same name, perhaps demonstrating changes over time? If so,
should I leave them as is, or should I consolidate them? If I consolidate,
would using the most current spelling facilitate or hinder research?

I'm a neophyte. You're help will be gratefully received.

[Ole Bjørn Darrud]

Hi

today's local municipals ("kommune") in eastern Telemark relevant for your question are
Notodden and Hjartdal.
Ref. eg. this map: http://www.norge.no/kart/Telemark/

Historic parishes Heddal (= Hitterdal) and subparish Gransherad form the basis for todays "Notodden". Pre 1912 "Hitterdal/Heddal" and "Gransherad" comprised all this in separate church records and censuses.

Historic parishes Hierdal (= subparishes Sauland, Tuddal and Hjartdal) form the basis for todays "Hjartdal". Hierdal = Hjartdal has separate churchrecords and cenuses.

Regards

Ole Bjørn