Normally there shouldn't be more than one primary accent (') per entry, the DUDEN can always be used as a reference. Secondary accents ('') are not indicated in the DUDEN. They occur mainly in phrases, compounds and prefix verbs.
Example: Aimee-und-Jaguar QEm''e:Untj'a:gua:r ''Offnungszeiten Q'9fnUNsts''aIt@n abbuchen Q'apb''u:x@n