More blocks in buffer cache than object on disk

In one of our 12.1.0.2 DBs, there's some discussion involving a table and/or its indexes. In gathering info about the table, I see that while the table size is 683264 blocks (from DBA_SEGMENTS), there appears to be 1071098 blocks in the buffer cache for that table, according to V$BH. That's ~8.4GB cache for a ~5.3GB table (8K block size). Seems....excessive.

Maybe my buffer cache query is at fault:

SELECT

     dbo.owner||'.'||dbo.object_name object_name,
     bh.objd,
     COUNT(*)*8192/1024/1024 size_mb,
     count(*) size_blocks
FROM
     dba_objects DBO,
     v$bh bh
WHERE
     dbo.data_object_id = bh.objd
     and dbo.object_name = 'MYTABLE'
GROUP BY
     dbo.owner,
     dbo.object_name,
     bh.objd;

If it matters, this instance is on AIX, has an SGA of ~130GB, non-ASM, non-AMM, and is a primary for ADG. It's been up for about 40 days. The ERP application that uses it gets bounced weekly due to middle tier Java entropy (so, no lingering transactions).

Thoughts?