When opening a document that was set to restart footnote numbering on each page, if the document is saved as a DOC then it reverts to continuous numbering *in MSWord only*. (LibreOffice DOES import with per-page numbering).
According to Linux bibisect43all, this has been true since at least LO3.5.
This is a companion to DOCX bug 92470. Use that bug's ODT attachment 116974 [details] which has per-page renumbering. When saving it as a .doc format, MSWord will still consider it to be "continuous" numbering.
proposed fix: https://gerrit.libreoffice.org/43622
Justin Luth committed a patch related to this issue.
It has been pushed to "master":
tdf#105381 ww8export: support footnote numbering per page
It will be available in 6.0.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.