No. There are lots of stories about various very long versions of Dune. The most common story that is Lynch had a 6-hour version and that the studio forced him down to 2. It's a myth. The theatrical cut is the only cut Lynch did.
https://en.wikipedia.org/wiki/Jodorowsky's_Dune
It may also be confusing Lynch's film with the 2000 Sci-Fi miniseries Frank Herbert's Dune, which totalled roughly 5 hours across three episodes.