The Spelling of a name

How many ways can a name be spelled?  The first time I see the name of my third great grand aunt, it is spelled Adina.  

1860 Adina P.
1880 Alphenia
1892 Cornelia
1900 Penina
1920 Perhine
1925 Perninne
1930 Pernine
1940 Diana P.

I looked at the spellings myself and they are as you see above.  I've checked family members and their ages to verify the correct families.  Census reports indicate that she is literate so I am baffled as to why her name is spelled differently in each report. The majority start with Per so I considered entering her in my family tree as Pernine.   I might presume that Adina is her first name and Pernine, or some form of it, is a middle name.  I believe that genealogical common sense tells me that the event closest to the event has a better chance of being correct.  I'll enter her in the family tree as Adina Pernine until I have more evidence of her name.

She's not a direct line ancestor.  I would normally not devote this much time and effort into her.  However, solving the spelling of her name is a challenge I will pursue!