Are these indexes redundant? I have two indexes on a table that will contain roughly 10-20 million records at a given moment.

Index 1

CREATE NONCLUSTERED INDEX [IX_NC_AccountNumber_UTC] ON [dbo].[LogWindow]
(
    [AccountNumber] ASC,
    [UTC] ASC
)
INCLUDE (   [Site],
    [Application],
    [Version],
    [Machine],
    [Context],
    [Severity],
    [Message],
    [Details]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO


Index 2

CREATE NONCLUSTERED INDEX [IX_NC_AccountNumber_UTC_Site_Context_Machine] ON [dbo].[LogWindow]
(
    [AccountNumber] ASC,
    [UTC] ASC,
    [Site] ASC,
    [Context] ASC,
    [Machine] ASC
)
INCLUDE (   [Application],
    [Version],
    [Severity],
    [Message],
    [Details],
    [Type]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO


The reason why I am currently using two indexes is because I am issuing two types of queries.  The first query only filters records based upon AccountNumber and UTC.  The second query filters records based upon those same columns, plus the additional Site, Context and Machine columns.

The second index is very similar to the first; it's just covering less columns because now they are part of the key indexed columns.

Does it make sense for me to have the first index when the second one is so similar with additional key columns?  Will SQL Server determine there is a benefit to using the first index over the second?
They are redundant. Second index should be usable by any query that would be using the first one.