AWR snap begin interval and end interval times are different between instances

This is my first time to post a question so if I'm in the wrong 'space' please direct me to the correct one.

We have a 2 node RAC DB (v12.0.1.0) running on Unix.  When looking at the data in dba_hist_snapshot I see, for the same snap_id's, my snap_timezone is different.

SELECT SNP.SNAP_ID

      ,SNP.INSTANCE_NUMBER

      ,SNP.BEGIN_INTERVAL_TIME

      ,SNP.END_INTERVAL_TIME

      ,SNP.SNAP_TIMEZONE

  FROM DBA_HIST_SNAPSHOT SNP

WHERE SNP.SNAP_ID = 9882

ORDER BY SNP.SNAP_ID, INSTANCE_NUMBER;

SNAP_ID     INSTANCE_NUMBER   BEGIN_INTERVAL_TIME             END_INTERVAL_TIME               SNAP_TIMEZONE