I would tend to write double-l, but Google gives me more single-l, so I'm guessing it's an Atlantic divide thing.
And I guess all the other *full words.
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I would say successfull is a typo. Neither Merriam-Webster nor Wiktionary mention it as an alternative spelling. The British National Corpus has 10695 cites for successful and exactly one for successfull. According to OneLook, 33 dictionaries have an entry for successful, but only Wordnik has a few cites for successfull (without a definition).
Edit: by popular request, I will add that the adverb successfully is written with two L's. Successfuly would be incorrect.