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Export a copy of your husband's database with File->Export, choosing file format OmniFocus document, and choosing a filename that will make it readily identifiable. Move that file to your computer. Open OmniFocus on your computer in the usual fashion, then go to the Finder and double-click the file with your husband's data. It will open up as a separate window, with the file name in the title (hence the suggestion about the name). Now you can drag and drop, copy and paste, fold, spindle, and mutilate your respective databases to your heart's content.

After you are done, if you have made changes to his data, close OmniFocus, and copy the file back to his machine. Open OmniFocus on his machine, select File->Restore to Database Backup... and choose the file you've transferred. That should replace his old database with the contents of the new file.