longtwocolumn
Provides a \twocolumn variant whose single-column content may break across multiple pages.
The package longtwocolumn came out of a request. It provides the command
\longtwocolumn — a variant of LaTeX's \twocolumn that allows the
single-column content of the optional argument to break across multiple pages.
The downside is that footnotes inside the optional argument are not currently
supported.
The package is hosted on GitLab under “KOMA-Script and Friends”. See the CTAN catalogue entry for more.