This is makeindex, version 2.15 [TeX Live 2011] (kpathsea + Thai support).
Scanning input file Hyperreftest.idx....done (6 entries accepted, 0 rejected).
Sorting entries....done (19 comparisons).
Generating output file Hyperreftest.ind....
## Warning (input = Hyperreftest.idx, line = 2; output = Hyperreftest.ind, line = 3):
   -- Conflicting entries: multiple encaps for the same page under same key.

## Warning (input = Hyperreftest.idx, line = 6; output = Hyperreftest.ind, line = 5):
   -- Conflicting entries: multiple encaps for the same page under same key.
done (12 lines written, 2 warnings).
Output written in Hyperreftest.ind.
Transcript written in Hyperreftest.ilg.