[DiapDealer]

As Doitsu mentioned, the entity doubling is a known bug caused by your system's version of libxml2, so there's no need to report it anyway. And downgrading Sigil won't fix the issue on that particular machine (because the problem is not with Sigil). So if you're interested in working around the issue, there's a few ways to go about it:

1) A few threads up (in the sticky section) there's a thread titled "Linux-only libxml2 bug that affects Sigil on newer systems" that contains instructions for installing a patched version of libxml2 to your existing Sigil install.

2) You could also try the unofficial Linux installer package (also found in the sticky thread section). It includes a patched version of libxml2.

3) You could build Sigil yourself. There's instructions in the docs folder of the source that tell how to build your own patched version of libxml2 along side of Sigil.

If you still wish to downgrade Sigil, I could tell you exactly how to remove 0.9.x, but I'd need to know how you installed it in the first place. To get the older version, you'd probably need to grab the source and build it yourself (instructions are in the docs folder).