Index Unique and Range scan showing db file scattered reads - is it index prefetch

While reviewing the results of a ADDM report, it shows 2 queries with a lot of potential to improve. However when we look at those queries, the associated wait events and plan of those queries, it shows an index unique scan and an index range scan -which is as it should be. However one of the top wait events is "db file scattered read". It was surprising to see multi block reads with an index unique/range scan! It seems that for the initial period of the test, these multi block reads result in lesser throughput. Infact on the x86 platform, after