drm/data/ResourceId_xxxxxx directory should be missing from project folder.
-- correct

The second time it gives callback that this is already purchased.
-- i guess you observe that IAP behavior in test mode. In live mode you should be able to buy the same item multiple times. Here live mode means application id is not the default value '000000' - six zeroes but a value assigned by Store during publishing process. That mess in behavior can be considered as a bug. To avoid it just follow IAP developer's guide recommendations:
  • DRM protected model supports automatic product restoration and thus does not allow multiple purchases of the same product
  • non-DRM model does not support automatic restoration and allows multiple purchases of the same product

I think it is worth to check FAQ also : http://support.publish.nokia.com/?cat=6&topic=57 and http://www.developer.nokia.com/Commu...netization-FAQ