Some Linux distributions -- such as Fedora -- have already taken action on these samples and removed them from the LMMS distribution for their platform. We too -- the upstream LMMS developers -- have a long term plan to remove all bundled samples that we're not sure of the origins of. Most samples will be removed with this effort and the `rave_*` samples will be part of that.
The commit history for these files goes back 13 years to the 2006 commit a63c20f by "Tobias Doerffel", the creator of LMMS. Unfortunately the source of these files stops there.
In defense of musikBear, we have had a similar copyright claim on a piece of art we use, specifically, the "flaming football (soccer ball)" used in our Kicker plugin. In the case of the Kicker logo, the artwork was legally obtained originally but the SVG was never saved. The SVG that we acquired was relicensed (CC0 does allow this) and the copy we had was slightly modified.
We resolved it by reverting the SVG to the original, CC0 version and adding a license file.
https://github.com/LMMS/artwork/commit/ ... 345aa2a54e
https://github.com/LMMS/artwork/commit/ ... 270bb2ef01
Anyway, I'll email Toby and see what he remembers. I can't find mention of them prior to this date, so the origin is still unknown. The fact that they contain "rave" in the file name suggests they were obtained directly from Marc Gminder's collection "Rave" collection. Some of his samples were distributed on "sample CDs". For example, the album "Marc Gminder – DanceMachine - Special Edition + 400 Space-Sounds" with contained over 1,000 samples was sold in Germany, suggesting this may have been released with a liberal license.
I'll reach out to Toby and see what he remembers around this time.