data loss around splits when tserver goes down

[Anthony F]

I have observed a loss of data when tservers fail during bulk ingest.  The
keys that are missing are right around the table's splits indicating that
data was lost when a tserver died during a split.  I am using Accumulo
1.5.0.  At around the same time, I observe the master logging a message
about "Found two locations for the same extent".  Can anyone shed light on
this behavior?  Are tserver failures during bulk ingest supposed to be
fault tolerant?