Hopper has been battling prostate cancer and in October canceled all travel plans to focus on treatment.
Hopper is seeking joint custody of the couple's 6-year-old daughter and offering to pay spousal support to Duffy.
The "Easy Rider" star last year finished shooting the second season of "Crash," a TV version of the Oscar-winning 2004 film that airs on the Starz network. Hopper also has several film projects in the works.
Phone and e-mail messages left for Hopper's manager, Sam Maydew, have not been returned.
