why does the Demantra Index Adviser suggest 2 worksheet indexes for each worksheet

I am trying to improve worksheet performance using the Index Adviser.  It is suggesting 2 worksheet indexes for each worksheet

here's an example

CREATE INDEX [WS_INDEX_2]_IDX ON MDP_MATRIX
(T_EP_EBS_CUST_CLASS_EP_ID, T_EP_L_ATT_2_EP_ID, T_EP_E1_ITEM_CAT_6_EP_ID, T_EP_P3_EP_ID, T_EP_SITE_EP_ID, FROM_DATE, UNTIL_DATE, LAST_UPDATE_DATE, SALES_DATA_LUD, T_EP_SITE_LUD, T_EP_EBS_CUST_CLASS_LUD, T_EP_P3_LUD)
TABLESPACE [TABLESPACE]
COMPUTE STATISTICS;

CREATE INDEX [WS_INDEX_2]_IDX ON MDP_MATRIX
(T_EP_EBS_CUST_CLASS_EP_ID, T_EP_L_ATT_2_EP_ID, T_EP_E1_ITEM_CAT_6_EP_ID, T_EP_P3_EP_ID, T_EP_SITE_EP_ID)