The use of the initial letter "w" does not constitute a mis-spelling but rather the common use of the Polish "w" rather than the Lithuanian "v" prior to WWI. You are correct in that the Lithuanian alphabet does not contain the letter "w", but this is only since the language was standardized after WWI.

Vaitukaitis is not a particularly common surname in Lithuania, since there are only 17 listings in the online phone book for Lithuania for this surname, including those with the ending "-iene" for married women and "-tye" for unmarried women. A few of the listings are in the south-western part of Lithuania, the old Suwalki province or gubernia of the Russian Empire, but there are a couple also from the northwest part of Lithuania.

John Peters