When loading an IMS database that has been unloaded using IBM's unload program, DFSURGU0, the IMSDBU LOAD option rejects 2 records as it cannot identify the segment name.
This is usually the root segment name minus the first 2 characters.

This is quite normal as the 2 rejected records are header and trailor records. You must make sure that LAYOUT(I) is specified on the LOAD options so that the correct positions for identification are used.