First of all i would like to understand the difference b/w often and oftenly.

Check these sentences.

I go to school often. or I go to school oftenly.

I oftenly go to school. or I often go to school.

I go oftenly to school. or I go often to school.
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Comments  (Page 3) 

It has an entry in the OED calling it "Now US regional (rare)." It no doubt owes it presence there to its antiquity, the first citation being from a million years ago, and not to its currency or correctness. It is patent illiterate hypercorrection outside of whatever pockets of dialect it might live in. I've never heard it.

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Wiki dictionary has the word "oftenly".However, I remember my primary school teacher used to insist that the word doesn't exist. I'm now confused.

I assumed it

Oftenly isn't a word. So the sentences where it's used are erroneous.
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