From the late 1960s up to 1980 they are carbons. In 1980 he started using a photocopier (or Xeroxing, as the kids say). Then in 1991 he switched from copies to computer printouts.
So up until 1980, the manuscripts were actually in his typewriter. After that they were just copies, but they were always hand dated and signed. Though I know of at least one case where Bukowski mistakenly sent out
an original typescript rather than a carbon (if you compare it to
the other manuscript from 11/27/79 you can see the difference).
To me the carbons have more value, since they were actually in his typewriter. But if you look at the prices manuscripts sell for, carbon vs. Xerox doesn't seem to make much of a difference. People will pay almost as much for a Xerox as a carbon.
Though at this point the price similarities may be due to the overall scarceness of manuscripts. Back when Scott Harrison was selling hundreds of manuscripts on eBay there was more of a price difference, and the Xeroxes sold for less.
All of the letters are original typescripts. He did not make copies of letters.
This brings up another question, which is, where are the original poem typescripts, at the Huntington, or in Martin's file cabinets?