I imported my manuscript from Word and many (but not all) of my apostrophe’s had been doubled. For example “Sara’s” had become “Sara’'s”.
If you have Word 2007-2013 installed, switching Scrivener to use the Microsoft Office importer should fix this. In Tools > Options, open the Import/Export tab, then click “Import Converters…” On the left, choose DOC or DOCX from the menu, whichever you’re using (or do this once for each) and then from the right choose the MS Office option. Once you’ve OK’d out of all that, try the import again.
If you don’t have a compatible version of Office installed to make these converters available, try resaving the document as RTF and then importing it to Scrivener.