IF and only if ABC.COLUMN2 is a (very) large column, and ABC.COLUMN1 is used by itself a lot, it might be worthwhile to keep both indexes.
You should also review sys.dm_db_index_usage_stats to see how often, and in what ways, each index is currently being used.
SQL DBA,SQL Server MVP(07, 08, 09)[size=2]Prosecutor James Blackburn, in closing argument in the Fatal Vision murders trial: If in the future, you should cry a tear, cry one for them [the murder victims]. If in the future, you should say a prayer, say one for them. And if in the future, you should light a candle, light one for them.[/size]