I found the same thing as Holly: some of the 2679 linear features I'm running through the tool have been flagged both as D and as N.
I thought I would familiarize myself with the tool by comparing a feature class in a file geodatabase to itself. To do this, I copied the original GDB and then pointed the Update Features to the first GDB and the Base Features to the second GDB and ran the tool with a Search Distance of .01m (our established standard tolerance). That's it, nothing else, none of the optional parameters filled in.
I would expect that the tool would return every record as 'NC' (No Change) because I haven't changed anything at all but...as Holly pointed out, some of the records are flagged as both 'N' (New) and 'D' (Deleted). An examination of the optional output table when I reran it shows that for many of the SRC_FID values, there are -1 values in the TGT_FID and further down, those exact same SRC_FID show up in the TGT_FID with a SRC_FID value of -1.
Why are these records not being matched? The GDBs are identical and all the records should be 'NC'. What am I missing?
TIA
Brian
ArcMap 10.2