Flag duplicates with DAX

uif19085  can you please test out the following meaure , you probably need a rowNum/Index Column

dup =
VAR __val =
    CALCULATE (
        [current],
        OFFSET (
            -1,
            DISTINCT ( ALL ( 'Table' ) ),
            ORDERBY ( 'Table'[Index] ),
            KEEP,
            PARTITIONBY ( 'Table'[id] )
        )
    )
VAR currentId =
    MAX ( 'Table'[id] )
VAR currentIndex =
    MAX ( 'Table'[Index] )
VAR dateCount =
    CALCULATE (
        DISTINCTCOUNT ( 'Table'[date] ),
        FILTER (
            ALL ( 'Table' ),
            'Table'[id] = currentId
                && 'Table'[Index] <= currentIndex
        )
    )
VAR final =
    SWITCH (
        TRUE (),
        __val == BLANK (), 1,
        [current] - 1 = __val
            && dateCount = 1, 0,
        1
    )
RETURN
    final

or like this

Measure = 
VAR currDate =
    MAX ( 'Table'[date] )
VAR currDate2 = currDate + 0
VAR currentId =
    MAX ( 'Table'[id] )
VAR currentIndex =
    MAX ( 'Table'[Index] )
VAR minIndexbyID =
    CALCULATE (
        [currentIndex],
        INDEX (
            1,
            DISTINCT ( ALL ( 'Table' ) ),
            ORDERBY ( 'Table'[Index] ),
            KEEP,
            PARTITIONBY ( 'Table'[id] )
        )
    )
VAR filterTbl1 =
    FILTER (
        ALL ( 'Table' ),
        'Table'[id] = currentId
            && 'Table'[Index] >= minIndexbyID
            && currentIndex >= 'Table'[Index]
    )
VAR filterTbl2 =
    FILTER (
        ALL ( 'Table' ),
        'Table'[id] = currentId
            && 'Table'[Index] >= minIndexbyID
    )
VAR leftTbl1 =
    SELECTCOLUMNS ( filterTbl1, "dt", 'Table'[date] + 0 )
VAR leftTbl2 =
    SELECTCOLUMNS ( filterTbl2, "dt", 'Table'[date] + 0 )
VAR rightTbl =
    SELECTCOLUMNS ( { currDate }, "dt", [Value] + 0 )
VAR dates1 =
    NATURALINNERJOIN ( leftTbl1, rightTbl )
VAR dates2 =
    NATURALINNERJOIN ( leftTbl2, rightTbl )
VAR val1 =
    COUNTROWS ( dates1 )
VAR val2 =
    COUNTROWS ( dates2 )
VAR ternary =
    SWITCH (
        TRUE (),
        val1 = 1
            && val2 = 1, val1 & "-unique entry",
        val1 = 1
            && val2 <> 1, val1 & "-has duplicate entry",
        "0" & "-has duplicate entry"
    )
RETURN
    ternary