The Debian packages with the script are - of course - created using a script. This has worked well for ages. Until January 2018. When the 17 January package was created, something caused the version number 2 to be used instead of 1.4.8 (the latter is used in the script and on the site).
I did not notice this and neither did anyone else apparently, as no-one reported it. Which makes me doubt the usefulness of continuing to maintain the package, by the way, but that's another matter.
Unfortunately, because of the way the package system works, it is not possible to put version 1.4.9 back to its correct number, as that would be less than 2. Hence the jump to version 2.0.1.