why u are getting the problem is we are doing mistake in the naming convention of the custom folder and as well as item clauses names which are u given in the one instance is not equal to another instance .so
what i am suggesting is please copy the files names and try it will definitely work.
Try re-importing and matching on Names and see if that helps.
Having End User Layer metadata out of sync and maintained in more than one place is a recipe for disaster. The best way to develop Discoverer metadata is to have a three-stage environment using Development, Test and Production.
You should never add new Production metadata without migrating from Test which in turn is migrated from Development. Adding new metadata in Production will cause the unique IDs to be updated. The next time you migrate from Test, checking the box to match on identifiers will cause problems. Of course if you also take the time to make sure than even identifiers are unique then you will not have any issues.